Android example source code file (LinearLayout.java)
The LinearLayout.java Android example source code/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.widget;
import com.android.internal.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.ViewDebug;
import android.view.ViewGroup;
import android.widget.RemoteViews.RemoteView;
/**
* A Layout that arranges its children in a single column or a single row. The direction of
* the row can be set by calling {@link #setOrientation(int) setOrientation()}.
* You can also specify gravity, which specifies the alignment of all the child elements by
* calling {@link #setGravity(int) setGravity()} or specify that specific children
* grow to fill up any remaining space in the layout by setting the <em>weight member of
* {@link android.widget.LinearLayout.LayoutParams LinearLayout.LayoutParams}.
* The default orientation is horizontal.
*
* <p>
* Also see {@link LinearLayout.LayoutParams android.widget.LinearLayout.LayoutParams}
* for layout attributes </p>
*/
@RemoteView
public class LinearLayout extends ViewGroup {
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
/**
* Whether the children of this layout are baseline aligned. Only applicable
* if {@link #mOrientation} is horizontal.
*/
@ViewDebug.ExportedProperty
private boolean mBaselineAligned = true;
/**
* If this layout is part of another layout that is baseline aligned,
* use the child at this index as the baseline.
*
* Note: this is orthogonal to {@link #mBaselineAligned}, which is concerned
* with whether the children of this layout are baseline aligned.
*/
@ViewDebug.ExportedProperty
private int mBaselineAlignedChildIndex = -1;
/**
* The additional offset to the child's baseline.
* We'll calculate the baseline of this layout as we measure vertically; for
* horizontal linear layouts, the offset of 0 is appropriate.
*/
@ViewDebug.ExportedProperty
private int mBaselineChildTop = 0;
@ViewDebug.ExportedProperty
private int mOrientation;
@ViewDebug.ExportedProperty(mapping = {
@ViewDebug.IntToString(from = -1, to = "NONE"),
@ViewDebug.IntToString(from = Gravity.NO_GRAVITY, to = "NONE"),
@ViewDebug.IntToString(from = Gravity.TOP, to = "TOP"),
@ViewDebug.IntToString(from = Gravity.BOTTOM, to = "BOTTOM"),
@ViewDebug.IntToString(from = Gravity.LEFT, to = "LEFT"),
@ViewDebug.IntToString(from = Gravity.RIGHT, to = "RIGHT"),
@ViewDebug.IntToString(from = Gravity.CENTER_VERTICAL, to = "CENTER_VERTICAL"),
@ViewDebug.IntToString(from = Gravity.FILL_VERTICAL, to = "FILL_VERTICAL"),
@ViewDebug.IntToString(from = Gravity.CENTER_HORIZONTAL, to = "CENTER_HORIZONTAL"),
@ViewDebug.IntToString(from = Gravity.FILL_HORIZONTAL, to = "FILL_HORIZONTAL"),
@ViewDebug.IntToString(from = Gravity.CENTER, to = "CENTER"),
@ViewDebug.IntToString(from = Gravity.FILL, to = "FILL")
})
private int mGravity = Gravity.LEFT | Gravity.TOP;
@ViewDebug.ExportedProperty
private int mTotalLength;
@ViewDebug.ExportedProperty
private float mWeightSum;
@ViewDebug.ExportedProperty
private boolean mUseLargestChild;
private int[] mMaxAscent;
private int[] mMaxDescent;
private static final int VERTICAL_GRAVITY_COUNT = 4;
private static final int INDEX_CENTER_VERTICAL = 0;
private static final int INDEX_TOP = 1;
private static final int INDEX_BOTTOM = 2;
private static final int INDEX_FILL = 3;
public LinearLayout(Context context) {
super(context);
}
public LinearLayout(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a =
context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.LinearLayout);
int index = a.getInt(com.android.internal.R.styleable.LinearLayout_orientation, -1);
if (index >= 0) {
setOrientation(index);
}
index = a.getInt(com.android.internal.R.styleable.LinearLayout_gravity, -1);
if (index >= 0) {
setGravity(index);
}
boolean baselineAligned = a.getBoolean(R.styleable.LinearLayout_baselineAligned, true);
if (!baselineAligned) {
setBaselineAligned(baselineAligned);
}
mWeightSum = a.getFloat(R.styleable.LinearLayout_weightSum, -1.0f);
mBaselineAlignedChildIndex =
a.getInt(com.android.internal.R.styleable.LinearLayout_baselineAlignedChildIndex, -1);
// TODO: Better name, add Java APIs, make it public
mUseLargestChild = a.getBoolean(R.styleable.LinearLayout_useLargestChild, false);
a.recycle();
}
/**
* <p>Indicates whether widgets contained within this layout are aligned
* on their baseline or not.</p>
*
* @return true when widgets are baseline-aligned, false otherwise
*/
public boolean isBaselineAligned() {
return mBaselineAligned;
}
/**
* <p>Defines whether widgets contained in this layout are
* baseline-aligned or not.</p>
*
* @param baselineAligned true to align widgets on their baseline,
* false otherwise
*
* @attr ref android.R.styleable#LinearLayout_baselineAligned
*/
@android.view.RemotableViewMethod
public void setBaselineAligned(boolean baselineAligned) {
mBaselineAligned = baselineAligned;
}
@Override
public int getBaseline() {
if (mBaselineAlignedChildIndex < 0) {
return super.getBaseline();
}
if (getChildCount() <= mBaselineAlignedChildIndex) {
throw new RuntimeException("mBaselineAlignedChildIndex of LinearLayout "
+ "set to an index that is out of bounds.");
}
final View child = getChildAt(mBaselineAlignedChildIndex);
final int childBaseline = child.getBaseline();
if (childBaseline == -1) {
if (mBaselineAlignedChildIndex == 0) {
// this is just the default case, safe to return -1
return -1;
}
// the user picked an index that points to something that doesn't
// know how to calculate its baseline.
throw new RuntimeException("mBaselineAlignedChildIndex of LinearLayout "
+ "points to a View that doesn't know how to get its baseline.");
}
// TODO: This should try to take into account the virtual offsets
// (See getNextLocationOffset and getLocationOffset)
// We should add to childTop:
// sum([getNextLocationOffset(getChildAt(i)) / i < mBaselineAlignedChildIndex])
// and also add:
// getLocationOffset(child)
int childTop = mBaselineChildTop;
if (mOrientation == VERTICAL) {
final int majorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
if (majorGravity != Gravity.TOP) {
switch (majorGravity) {
case Gravity.BOTTOM:
childTop = mBottom - mTop - mPaddingBottom - mTotalLength;
break;
case Gravity.CENTER_VERTICAL:
childTop += ((mBottom - mTop - mPaddingTop - mPaddingBottom) -
mTotalLength) / 2;
break;
}
}
}
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
return childTop + lp.topMargin + childBaseline;
}
/**
* @return The index of the child that will be used if this layout is
* part of a larger layout that is baseline aligned, or -1 if none has
* been set.
*/
public int getBaselineAlignedChildIndex() {
return mBaselineAlignedChildIndex;
}
/**
* @param i The index of the child that will be used if this layout is
* part of a larger layout that is baseline aligned.
*
* @attr ref android.R.styleable#LinearLayout_baselineAlignedChildIndex
*/
@android.view.RemotableViewMethod
public void setBaselineAlignedChildIndex(int i) {
if ((i < 0) || (i >= getChildCount())) {
throw new IllegalArgumentException("base aligned child index out "
+ "of range (0, " + getChildCount() + ")");
}
mBaselineAlignedChildIndex = i;
}
/**
* <p>Returns the view at the specified index. This method can be overriden
* to take into account virtual children. Refer to
* {@link android.widget.TableLayout} and {@link android.widget.TableRow}
* for an example.</p>
*
* @param index the child's index
* @return the child at the specified index
*/
View getVirtualChildAt(int index) {
return getChildAt(index);
}
/**
* <p>Returns the virtual number of children. This number might be different
* than the actual number of children if the layout can hold virtual
* children. Refer to
* {@link android.widget.TableLayout} and {@link android.widget.TableRow}
* for an example.</p>
*
* @return the virtual number of children
*/
int getVirtualChildCount() {
return getChildCount();
}
/**
* Returns the desired weights sum.
*
* @return A number greater than 0.0f if the weight sum is defined, or
* a number lower than or equals to 0.0f if not weight sum is
* to be used.
*/
public float getWeightSum() {
return mWeightSum;
}
/**
* Defines the desired weights sum. If unspecified the weights sum is computed
* at layout time by adding the layout_weight of each child.
*
* This can be used for instance to give a single child 50% of the total
* available space by giving it a layout_weight of 0.5 and setting the
* weightSum to 1.0.
*
* @param weightSum a number greater than 0.0f, or a number lower than or equals
* to 0.0f if the weight sum should be computed from the children's
* layout_weight
*/
@android.view.RemotableViewMethod
public void setWeightSum(float weightSum) {
mWeightSum = Math.max(0.0f, weightSum);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (mOrientation == VERTICAL) {
measureVertical(widthMeasureSpec, heightMeasureSpec);
} else {
measureHorizontal(widthMeasureSpec, heightMeasureSpec);
}
}
/**
* Measures the children when the orientation of this LinearLayout is set
* to {@link #VERTICAL}.
*
* @param widthMeasureSpec Horizontal space requirements as imposed by the parent.
* @param heightMeasureSpec Vertical space requirements as imposed by the parent.
*
* @see #getOrientation()
* @see #setOrientation(int)
* @see #onMeasure(int, int)
*/
void measureVertical(int widthMeasureSpec, int heightMeasureSpec) {
mTotalLength = 0;
int maxWidth = 0;
int alternativeMaxWidth = 0;
int weightedMaxWidth = 0;
boolean allFillParent = true;
float totalWeight = 0;
final int count = getVirtualChildCount();
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
boolean matchWidth = false;
final int baselineChildIndex = mBaselineAlignedChildIndex;
final boolean useLargestChild = mUseLargestChild;
int largestChildHeight = Integer.MIN_VALUE;
// See how tall everyone is. Also remember max width.
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child == null) {
mTotalLength += measureNullChild(i);
continue;
}
if (child.getVisibility() == View.GONE) {
i += getChildrenSkipCount(child, i);
continue;
}
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
totalWeight += lp.weight;
if (heightMode == MeasureSpec.EXACTLY && lp.height == 0 && lp.weight > 0) {
// Optimization: don't bother measuring children who are going to use
// leftover space. These views will get measured again down below if
// there is any leftover space.
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + lp.topMargin + lp.bottomMargin);
} else {
int oldHeight = Integer.MIN_VALUE;
if (lp.height == 0 && lp.weight > 0) {
// heightMode is either UNSPECIFIED or AT_MOST, and this
// child wanted to stretch to fill available space.
// Translate that to WRAP_CONTENT so that it does not end up
// with a height of 0
oldHeight = 0;
lp.height = LayoutParams.WRAP_CONTENT;
}
// Determine how big this child would like to be. If this or
// previous children have given a weight, then we allow it to
// use all available space (and we will shrink things later
// if needed).
measureChildBeforeLayout(
child, i, widthMeasureSpec, 0, heightMeasureSpec,
totalWeight == 0 ? mTotalLength : 0);
if (oldHeight != Integer.MIN_VALUE) {
lp.height = oldHeight;
}
final int childHeight = child.getMeasuredHeight();
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + childHeight + lp.topMargin +
lp.bottomMargin + getNextLocationOffset(child));
if (useLargestChild) {
largestChildHeight = Math.max(childHeight, largestChildHeight);
}
}
/**
* If applicable, compute the additional offset to the child's baseline
* we'll need later when asked {@link #getBaseline}.
*/
if ((baselineChildIndex >= 0) && (baselineChildIndex == i + 1)) {
mBaselineChildTop = mTotalLength;
}
// if we are trying to use a child index for our baseline, the above
// book keeping only works if there are no children above it with
// weight. fail fast to aid the developer.
if (i < baselineChildIndex && lp.weight > 0) {
throw new RuntimeException("A child of LinearLayout with index "
+ "less than mBaselineAlignedChildIndex has weight > 0, which "
+ "won't work. Either remove the weight, or don't set "
+ "mBaselineAlignedChildIndex.");
}
boolean matchWidthLocally = false;
if (widthMode != MeasureSpec.EXACTLY && lp.width == LayoutParams.MATCH_PARENT) {
// The width of the linear layout will scale, and at least one
// child said it wanted to match our width. Set a flag
// indicating that we need to remeasure at least that view when
// we know our width.
matchWidth = true;
matchWidthLocally = true;
}
final int margin = lp.leftMargin + lp.rightMargin;
final int measuredWidth = child.getMeasuredWidth() + margin;
maxWidth = Math.max(maxWidth, measuredWidth);
allFillParent = allFillParent && lp.width == LayoutParams.MATCH_PARENT;
if (lp.weight > 0) {
/*
* Widths of weighted Views are bogus if we end up
* remeasuring, so keep them separate.
*/
weightedMaxWidth = Math.max(weightedMaxWidth,
matchWidthLocally ? margin : measuredWidth);
} else {
alternativeMaxWidth = Math.max(alternativeMaxWidth,
matchWidthLocally ? margin : measuredWidth);
}
i += getChildrenSkipCount(child, i);
}
if (useLargestChild && heightMode == MeasureSpec.AT_MOST) {
mTotalLength = 0;
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child == null) {
mTotalLength += measureNullChild(i);
continue;
}
if (child.getVisibility() == GONE) {
i += getChildrenSkipCount(child, i);
continue;
}
final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
child.getLayoutParams();
// Account for negative margins
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + largestChildHeight +
lp.topMargin + lp.bottomMargin + getNextLocationOffset(child));
}
}
// Add in our padding
mTotalLength += mPaddingTop + mPaddingBottom;
int heightSize = mTotalLength;
// Check against our minimum height
heightSize = Math.max(heightSize, getSuggestedMinimumHeight());
// Reconcile our calculated size with the heightMeasureSpec
heightSize = resolveSize(heightSize, heightMeasureSpec);
// Either expand children with weight to take up available space or
// shrink them if they extend beyond our current bounds
int delta = heightSize - mTotalLength;
if (delta != 0 && totalWeight > 0.0f) {
float weightSum = mWeightSum > 0.0f ? mWeightSum : totalWeight;
mTotalLength = 0;
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child.getVisibility() == View.GONE) {
continue;
}
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
float childExtra = lp.weight;
if (childExtra > 0) {
// Child said it could absorb extra space -- give him his share
int share = (int) (childExtra * delta / weightSum);
weightSum -= childExtra;
delta -= share;
final int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
mPaddingLeft + mPaddingRight +
lp.leftMargin + lp.rightMargin, lp.width);
// TODO: Use a field like lp.isMeasured to figure out if this
// child has been previously measured
if ((lp.height != 0) || (heightMode != MeasureSpec.EXACTLY)) {
// child was measured once already above...
// base new measurement on stored values
int childHeight = child.getMeasuredHeight() + share;
if (childHeight < 0) {
childHeight = 0;
}
child.measure(childWidthMeasureSpec,
MeasureSpec.makeMeasureSpec(childHeight, MeasureSpec.EXACTLY));
} else {
// child was skipped in the loop above.
// Measure for this first time here
child.measure(childWidthMeasureSpec,
MeasureSpec.makeMeasureSpec(share > 0 ? share : 0,
MeasureSpec.EXACTLY));
}
}
final int margin = lp.leftMargin + lp.rightMargin;
final int measuredWidth = child.getMeasuredWidth() + margin;
maxWidth = Math.max(maxWidth, measuredWidth);
boolean matchWidthLocally = widthMode != MeasureSpec.EXACTLY &&
lp.width == LayoutParams.MATCH_PARENT;
alternativeMaxWidth = Math.max(alternativeMaxWidth,
matchWidthLocally ? margin : measuredWidth);
allFillParent = allFillParent && lp.width == LayoutParams.MATCH_PARENT;
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + child.getMeasuredHeight() +
lp.topMargin + lp.bottomMargin + getNextLocationOffset(child));
}
// Add in our padding
mTotalLength += mPaddingTop + mPaddingBottom;
// TODO: Should we recompute the heightSpec based on the new total length?
} else {
alternativeMaxWidth = Math.max(alternativeMaxWidth,
weightedMaxWidth);
}
if (!allFillParent && widthMode != MeasureSpec.EXACTLY) {
maxWidth = alternativeMaxWidth;
}
maxWidth += mPaddingLeft + mPaddingRight;
// Check against our minimum width
maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec), heightSize);
if (matchWidth) {
forceUniformWidth(count, heightMeasureSpec);
}
}
private void forceUniformWidth(int count, int heightMeasureSpec) {
// Pretend that the linear layout has an exact size.
int uniformMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(),
MeasureSpec.EXACTLY);
for (int i = 0; i< count; ++i) {
final View child = getVirtualChildAt(i);
if (child.getVisibility() != GONE) {
LinearLayout.LayoutParams lp = ((LinearLayout.LayoutParams)child.getLayoutParams());
if (lp.width == LayoutParams.MATCH_PARENT) {
// Temporarily force children to reuse their old measured height
// FIXME: this may not be right for something like wrapping text?
int oldHeight = lp.height;
lp.height = child.getMeasuredHeight();
// Remeasue with new dimensions
measureChildWithMargins(child, uniformMeasureSpec, 0, heightMeasureSpec, 0);
lp.height = oldHeight;
}
}
}
}
/**
* Measures the children when the orientation of this LinearLayout is set
* to {@link #HORIZONTAL}.
*
* @param widthMeasureSpec Horizontal space requirements as imposed by the parent.
* @param heightMeasureSpec Vertical space requirements as imposed by the parent.
*
* @see #getOrientation()
* @see #setOrientation(int)
* @see #onMeasure(int, int)
*/
void measureHorizontal(int widthMeasureSpec, int heightMeasureSpec) {
mTotalLength = 0;
int maxHeight = 0;
int alternativeMaxHeight = 0;
int weightedMaxHeight = 0;
boolean allFillParent = true;
float totalWeight = 0;
final int count = getVirtualChildCount();
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
boolean matchHeight = false;
if (mMaxAscent == null || mMaxDescent == null) {
mMaxAscent = new int[VERTICAL_GRAVITY_COUNT];
mMaxDescent = new int[VERTICAL_GRAVITY_COUNT];
}
final int[] maxAscent = mMaxAscent;
final int[] maxDescent = mMaxDescent;
maxAscent[0] = maxAscent[1] = maxAscent[2] = maxAscent[3] = -1;
maxDescent[0] = maxDescent[1] = maxDescent[2] = maxDescent[3] = -1;
final boolean baselineAligned = mBaselineAligned;
final boolean useLargestChild = mUseLargestChild;
final boolean isExactly = widthMode == MeasureSpec.EXACTLY;
int largestChildWidth = Integer.MIN_VALUE;
// See how wide everyone is. Also remember max height.
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child == null) {
mTotalLength += measureNullChild(i);
continue;
}
if (child.getVisibility() == GONE) {
i += getChildrenSkipCount(child, i);
continue;
}
final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
child.getLayoutParams();
totalWeight += lp.weight;
if (widthMode == MeasureSpec.EXACTLY && lp.width == 0 && lp.weight > 0) {
// Optimization: don't bother measuring children who are going to use
// leftover space. These views will get measured again down below if
// there is any leftover space.
if (isExactly) {
mTotalLength += lp.leftMargin + lp.rightMargin;
} else {
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength +
lp.leftMargin + lp.rightMargin);
}
// Baseline alignment requires to measure widgets to obtain the
// baseline offset (in particular for TextViews). The following
// defeats the optimization mentioned above. Allow the child to
// use as much space as it wants because we can shrink things
// later (and re-measure).
if (baselineAligned) {
final int freeSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
child.measure(freeSpec, freeSpec);
}
} else {
int oldWidth = Integer.MIN_VALUE;
if (lp.width == 0 && lp.weight > 0) {
// widthMode is either UNSPECIFIED or AT_MOST, and this
// child
// wanted to stretch to fill available space. Translate that to
// WRAP_CONTENT so that it does not end up with a width of 0
oldWidth = 0;
lp.width = LayoutParams.WRAP_CONTENT;
}
// Determine how big this child would like to be. If this or
// previous children have given a weight, then we allow it to
// use all available space (and we will shrink things later
// if needed).
measureChildBeforeLayout(child, i, widthMeasureSpec,
totalWeight == 0 ? mTotalLength : 0,
heightMeasureSpec, 0);
if (oldWidth != Integer.MIN_VALUE) {
lp.width = oldWidth;
}
final int childWidth = child.getMeasuredWidth();
if (isExactly) {
mTotalLength += childWidth + lp.leftMargin + lp.rightMargin +
getNextLocationOffset(child);
} else {
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + childWidth + lp.leftMargin +
lp.rightMargin + getNextLocationOffset(child));
}
if (useLargestChild) {
largestChildWidth = Math.max(childWidth, largestChildWidth);
}
}
boolean matchHeightLocally = false;
if (heightMode != MeasureSpec.EXACTLY && lp.height == LayoutParams.MATCH_PARENT) {
// The height of the linear layout will scale, and at least one
// child said it wanted to match our height. Set a flag indicating that
// we need to remeasure at least that view when we know our height.
matchHeight = true;
matchHeightLocally = true;
}
final int margin = lp.topMargin + lp.bottomMargin;
final int childHeight = child.getMeasuredHeight() + margin;
if (baselineAligned) {
final int childBaseline = child.getBaseline();
if (childBaseline != -1) {
// Translates the child's vertical gravity into an index
// in the range 0..VERTICAL_GRAVITY_COUNT
final int gravity = (lp.gravity < 0 ? mGravity : lp.gravity)
& Gravity.VERTICAL_GRAVITY_MASK;
final int index = ((gravity >> Gravity.AXIS_Y_SHIFT)
& ~Gravity.AXIS_SPECIFIED) >> 1;
maxAscent[index] = Math.max(maxAscent[index], childBaseline);
maxDescent[index] = Math.max(maxDescent[index], childHeight - childBaseline);
}
}
maxHeight = Math.max(maxHeight, childHeight);
allFillParent = allFillParent && lp.height == LayoutParams.MATCH_PARENT;
if (lp.weight > 0) {
/*
* Heights of weighted Views are bogus if we end up
* remeasuring, so keep them separate.
*/
weightedMaxHeight = Math.max(weightedMaxHeight,
matchHeightLocally ? margin : childHeight);
} else {
alternativeMaxHeight = Math.max(alternativeMaxHeight,
matchHeightLocally ? margin : childHeight);
}
i += getChildrenSkipCount(child, i);
}
// Check mMaxAscent[INDEX_TOP] first because it maps to Gravity.TOP,
// the most common case
if (maxAscent[INDEX_TOP] != -1 ||
maxAscent[INDEX_CENTER_VERTICAL] != -1 ||
maxAscent[INDEX_BOTTOM] != -1 ||
maxAscent[INDEX_FILL] != -1) {
final int ascent = Math.max(maxAscent[INDEX_FILL],
Math.max(maxAscent[INDEX_CENTER_VERTICAL],
Math.max(maxAscent[INDEX_TOP], maxAscent[INDEX_BOTTOM])));
final int descent = Math.max(maxDescent[INDEX_FILL],
Math.max(maxDescent[INDEX_CENTER_VERTICAL],
Math.max(maxDescent[INDEX_TOP], maxDescent[INDEX_BOTTOM])));
maxHeight = Math.max(maxHeight, ascent + descent);
}
if (useLargestChild && widthMode == MeasureSpec.AT_MOST) {
mTotalLength = 0;
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child == null) {
mTotalLength += measureNullChild(i);
continue;
}
if (child.getVisibility() == GONE) {
i += getChildrenSkipCount(child, i);
continue;
}
final LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)
child.getLayoutParams();
if (isExactly) {
mTotalLength += largestChildWidth + lp.leftMargin + lp.rightMargin +
getNextLocationOffset(child);
} else {
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + largestChildWidth +
lp.leftMargin + lp.rightMargin + getNextLocationOffset(child));
}
}
}
// Add in our padding
mTotalLength += mPaddingLeft + mPaddingRight;
int widthSize = mTotalLength;
// Check against our minimum width
widthSize = Math.max(widthSize, getSuggestedMinimumWidth());
// Reconcile our calculated size with the widthMeasureSpec
widthSize = resolveSize(widthSize, widthMeasureSpec);
// Either expand children with weight to take up available space or
// shrink them if they extend beyond our current bounds
int delta = widthSize - mTotalLength;
if (delta != 0 && totalWeight > 0.0f) {
float weightSum = mWeightSum > 0.0f ? mWeightSum : totalWeight;
maxAscent[0] = maxAscent[1] = maxAscent[2] = maxAscent[3] = -1;
maxDescent[0] = maxDescent[1] = maxDescent[2] = maxDescent[3] = -1;
maxHeight = -1;
mTotalLength = 0;
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child == null || child.getVisibility() == View.GONE) {
continue;
}
final LinearLayout.LayoutParams lp =
(LinearLayout.LayoutParams) child.getLayoutParams();
float childExtra = lp.weight;
if (childExtra > 0) {
// Child said it could absorb extra space -- give him his share
int share = (int) (childExtra * delta / weightSum);
weightSum -= childExtra;
delta -= share;
final int childHeightMeasureSpec = getChildMeasureSpec(
heightMeasureSpec,
mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin,
lp.height);
// TODO: Use a field like lp.isMeasured to figure out if this
// child has been previously measured
if ((lp.width != 0) || (widthMode != MeasureSpec.EXACTLY)) {
// child was measured once already above ... base new measurement
// on stored values
int childWidth = child.getMeasuredWidth() + share;
if (childWidth < 0) {
childWidth = 0;
}
child.measure(
MeasureSpec.makeMeasureSpec(childWidth, MeasureSpec.EXACTLY),
childHeightMeasureSpec);
} else {
// child was skipped in the loop above. Measure for this first time here
child.measure(MeasureSpec.makeMeasureSpec(
share > 0 ? share : 0, MeasureSpec.EXACTLY),
childHeightMeasureSpec);
}
}
if (isExactly) {
mTotalLength += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin +
getNextLocationOffset(child);
} else {
final int totalLength = mTotalLength;
mTotalLength = Math.max(totalLength, totalLength + child.getMeasuredWidth() +
lp.leftMargin + lp.rightMargin + getNextLocationOffset(child));
}
boolean matchHeightLocally = heightMode != MeasureSpec.EXACTLY &&
lp.height == LayoutParams.MATCH_PARENT;
final int margin = lp.topMargin + lp .bottomMargin;
int childHeight = child.getMeasuredHeight() + margin;
maxHeight = Math.max(maxHeight, childHeight);
alternativeMaxHeight = Math.max(alternativeMaxHeight,
matchHeightLocally ? margin : childHeight);
allFillParent = allFillParent && lp.height == LayoutParams.MATCH_PARENT;
if (baselineAligned) {
final int childBaseline = child.getBaseline();
if (childBaseline != -1) {
// Translates the child's vertical gravity into an index in the range 0..2
final int gravity = (lp.gravity < 0 ? mGravity : lp.gravity)
& Gravity.VERTICAL_GRAVITY_MASK;
final int index = ((gravity >> Gravity.AXIS_Y_SHIFT)
& ~Gravity.AXIS_SPECIFIED) >> 1;
maxAscent[index] = Math.max(maxAscent[index], childBaseline);
maxDescent[index] = Math.max(maxDescent[index],
childHeight - childBaseline);
}
}
}
// Add in our padding
mTotalLength += mPaddingLeft + mPaddingRight;
// TODO: Should we update widthSize with the new total length?
// Check mMaxAscent[INDEX_TOP] first because it maps to Gravity.TOP,
// the most common case
if (maxAscent[INDEX_TOP] != -1 ||
maxAscent[INDEX_CENTER_VERTICAL] != -1 ||
maxAscent[INDEX_BOTTOM] != -1 ||
maxAscent[INDEX_FILL] != -1) {
final int ascent = Math.max(maxAscent[INDEX_FILL],
Math.max(maxAscent[INDEX_CENTER_VERTICAL],
Math.max(maxAscent[INDEX_TOP], maxAscent[INDEX_BOTTOM])));
final int descent = Math.max(maxDescent[INDEX_FILL],
Math.max(maxDescent[INDEX_CENTER_VERTICAL],
Math.max(maxDescent[INDEX_TOP], maxDescent[INDEX_BOTTOM])));
maxHeight = Math.max(maxHeight, ascent + descent);
}
} else {
alternativeMaxHeight = Math.max(alternativeMaxHeight, weightedMaxHeight);
}
if (!allFillParent && heightMode != MeasureSpec.EXACTLY) {
maxHeight = alternativeMaxHeight;
}
maxHeight += mPaddingTop + mPaddingBottom;
// Check against our minimum height
maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
setMeasuredDimension(widthSize, resolveSize(maxHeight, heightMeasureSpec));
if (matchHeight) {
forceUniformHeight(count, widthMeasureSpec);
}
}
private void forceUniformHeight(int count, int widthMeasureSpec) {
// Pretend that the linear layout has an exact size. This is the measured height of
// ourselves. The measured height should be the max height of the children, changed
// to accomodate the heightMesureSpec from the parent
int uniformMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredHeight(),
MeasureSpec.EXACTLY);
for (int i = 0; i < count; ++i) {
final View child = getVirtualChildAt(i);
if (child.getVisibility() != GONE) {
LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) child.getLayoutParams();
if (lp.height == LayoutParams.MATCH_PARENT) {
// Temporarily force children to reuse their old measured width
// FIXME: this may not be right for something like wrapping text?
int oldWidth = lp.width;
lp.width = child.getMeasuredWidth();
// Remeasure with new dimensions
measureChildWithMargins(child, widthMeasureSpec, 0, uniformMeasureSpec, 0);
lp.width = oldWidth;
}
}
}
}
/**
* <p>Returns the number of children to skip after measuring/laying out
* the specified child.</p>
*
* @param child the child after which we want to skip children
* @param index the index of the child after which we want to skip children
* @return the number of children to skip, 0 by default
*/
int getChildrenSkipCount(View child, int index) {
return 0;
}
/**
* <p>Returns the size (width or height) that should be occupied by a null
* child.</p>
*
* @param childIndex the index of the null child
* @return the width or height of the child depending on the orientation
*/
int measureNullChild(int childIndex) {
return 0;
}
/**
* <p>Measure the child according to the parent's measure specs. This
* method should be overriden by subclasses to force the sizing of
* children. This method is called by {@link #measureVertical(int, int)} and
* {@link #measureHorizontal(int, int)}.</p>
*
* @param child the child to measure
* @param childIndex the index of the child in this view
* @param widthMeasureSpec horizontal space requirements as imposed by the parent
* @param totalWidth extra space that has been used up by the parent horizontally
* @param heightMeasureSpec vertical space requirements as imposed by the parent
* @param totalHeight extra space that has been used up by the parent vertically
*/
void measureChildBeforeLayout(View child, int childIndex,
int widthMeasureSpec, int totalWidth, int heightMeasureSpec,
int totalHeight) {
measureChildWithMargins(child, widthMeasureSpec, totalWidth,
heightMeasureSpec, totalHeight);
}
/**
* <p>Return the location offset of the specified child. This can be used
* by subclasses to change the location of a given widget.</p>
*
* @param child the child for which to obtain the location offset
* @return the location offset in pixels
*/
int getLocationOffset(View child) {
return 0;
}
/**
* <p>Return the size offset of the next sibling of the specified child.
* This can be used by subclasses to change the location of the widget
* following <code>child.
*
* @param child the child whose next sibling will be moved
* @return the location offset of the next child in pixels
*/
int getNextLocationOffset(View child) {
return 0;
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (mOrientation == VERTICAL) {
layoutVertical();
} else {
layoutHorizontal();
}
}
/**
* Position the children during a layout pass if the orientation of this
* LinearLayout is set to {@link #VERTICAL}.
*
* @see #getOrientation()
* @see #setOrientation(int)
* @see #onLayout(boolean, int, int, int, int)
*/
void layoutVertical() {
final int paddingLeft = mPaddingLeft;
int childTop = mPaddingTop;
int childLeft;
// Where right end of child should go
final int width = mRight - mLeft;
int childRight = width - mPaddingRight;
// Space available for child
int childSpace = width - paddingLeft - mPaddingRight;
final int count = getVirtualChildCount();
final int majorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
final int minorGravity = mGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
if (majorGravity != Gravity.TOP) {
switch (majorGravity) {
case Gravity.BOTTOM:
// mTotalLength contains the padding already, we add the top
// padding to compensate
childTop = mBottom - mTop + mPaddingTop - mTotalLength;
break;
case Gravity.CENTER_VERTICAL:
childTop += ((mBottom - mTop) - mTotalLength) / 2;
break;
}
}
for (int i = 0; i < count; i++) {
final View child = getVirtualChildAt(i);
if (child == null) {
childTop += measureNullChild(i);
} else if (child.getVisibility() != GONE) {
final int childWidth = child.getMeasuredWidth();
final int childHeight = child.getMeasuredHeight();
final LinearLayout.LayoutParams lp =
(LinearLayout.LayoutParams) child.getLayoutParams();
int gravity = lp.gravity;
if (gravity < 0) {
gravity = minorGravity;
}
switch (gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
case Gravity.LEFT:
childLeft = paddingLeft + lp.leftMargin;
break;
case Gravity.CENTER_HORIZONTAL:
childLeft = paddingLeft + ((childSpace - childWidth) / 2)
+ lp.leftMargin - lp.rightMargin;
break;
case Gravity.RIGHT:
childLeft = childRight - childWidth - lp.rightMargin;
break;
default:
childLeft = paddingLeft;
break;
}
childTop += lp.topMargin;
setChildFrame(child, childLeft, childTop + getLocationOffset(child),
childWidth, childHeight);
childTop += childHeight + lp.bottomMargin + getNextLocationOffset(child);
i += getChildrenSkipCount(child, i);
}
}
}
/**
* Position the children during a layout pass if the orientation of this
* LinearLayout is set to {@link #HORIZONTAL}.
*
* @see #getOrientation()
* @see #setOrientation(int)
* @see #onLayout(boolean, int, int, int, int)
*/
void layoutHorizontal() {
final int paddingTop = mPaddingTop;
int childTop;
int childLeft = mPaddingLeft;
// Where bottom of child should go
final int height = mBottom - mTop;
int childBottom = height - mPaddingBottom;
// Space available for child
int childSpace = height - paddingTop - mPaddingBottom;
final int count = getVirtualChildCount();
final int majorGravity = mGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
final int minorGravity = mGravity & Gravity.VERTICAL_GRAVITY_MASK;
final boolean baselineAligned = mBaselineAligned;
final int[] maxAscent = mMaxAscent;
final int[] maxDescent = mMaxDescent;
if (majorGravity != Gravity.LEFT) {
switch (majorGravity) {
case Gravity.RIGHT:
// mTotalLength contains the padding already, we add the left
// padding to compensate
childLeft = mRight - mLeft + mPaddingLeft - mTotalLength;
break;
case Gravity.CENTER_HORIZONTAL:
childLeft += ((mRight - mLeft) - mTotalLength) / 2;
break;
}
}
for (int i = 0; i < count; i++) {
final View child = getVirtualChildAt(i);
if (child == null) {
childLeft += measureNullChild(i);
} else if (child.getVisibility() != GONE) {
final int childWidth = child.getMeasuredWidth();
final int childHeight = child.getMeasuredHeight();
int childBaseline = -1;
final LinearLayout.LayoutParams lp =
(LinearLayout.LayoutParams) child.getLayoutParams();
if (baselineAligned && lp.height != LayoutParams.MATCH_PARENT) {
childBaseline = child.getBaseline();
}
int gravity = lp.gravity;
if (gravity < 0) {
gravity = minorGravity;
}
switch (gravity & Gravity.VERTICAL_GRAVITY_MASK) {
case Gravity.TOP:
childTop = paddingTop + lp.topMargin;
if (childBaseline != -1) {
childTop += maxAscent[INDEX_TOP] - childBaseline;
}
break;
case Gravity.CENTER_VERTICAL:
// Removed support for baseline alignment when layout_gravity or
// gravity == center_vertical. See bug #1038483.
// Keep the code around if we need to re-enable this feature
// if (childBaseline != -1) {
// // Align baselines vertically only if the child is smaller than us
// if (childSpace - childHeight > 0) {
// childTop = paddingTop + (childSpace / 2) - childBaseline;
// } else {
// childTop = paddingTop + (childSpace - childHeight) / 2;
// }
// } else {
childTop = paddingTop + ((childSpace - childHeight) / 2)
+ lp.topMargin - lp.bottomMargin;
break;
case Gravity.BOTTOM:
childTop = childBottom - childHeight - lp.bottomMargin;
if (childBaseline != -1) {
int descent = child.getMeasuredHeight() - childBaseline;
childTop -= (maxDescent[INDEX_BOTTOM] - descent);
}
break;
default:
childTop = paddingTop;
break;
}
childLeft += lp.leftMargin;
setChildFrame(child, childLeft + getLocationOffset(child), childTop,
childWidth, childHeight);
childLeft += childWidth + lp.rightMargin +
getNextLocationOffset(child);
i += getChildrenSkipCount(child, i);
}
}
}
private void setChildFrame(View child, int left, int top, int width, int height) {
child.layout(left, top, left + width, top + height);
}
/**
* Should the layout be a column or a row.
* @param orientation Pass HORIZONTAL or VERTICAL. Default
* value is HORIZONTAL.
*
* @attr ref android.R.styleable#LinearLayout_orientation
*/
public void setOrientation(int orientation) {
if (mOrientation != orientation) {
mOrientation = orientation;
requestLayout();
}
}
/**
* Returns the current orientation.
*
* @return either {@link #HORIZONTAL} or {@link #VERTICAL}
*/
public int getOrientation() {
return mOrientation;
}
/**
* Describes how the child views are positioned. Defaults to GRAVITY_TOP. If
* this layout has a VERTICAL orientation, this controls where all the child
* views are placed if there is extra vertical space. If this layout has a
* HORIZONTAL orientation, this controls the alignment of the children.
*
* @param gravity See {@link android.view.Gravity}
*
* @attr ref android.R.styleable#LinearLayout_gravity
*/
@android.view.RemotableViewMethod
public void setGravity(int gravity) {
if (mGravity != gravity) {
if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == 0) {
gravity |= Gravity.LEFT;
}
if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == 0) {
gravity |= Gravity.TOP;
}
mGravity = gravity;
requestLayout();
}
}
@android.view.RemotableViewMethod
public void setHorizontalGravity(int horizontalGravity) {
final int gravity = horizontalGravity & Gravity.HORIZONTAL_GRAVITY_MASK;
if ((mGravity & Gravity.HORIZONTAL_GRAVITY_MASK) != gravity) {
mGravity = (mGravity & ~Gravity.HORIZONTAL_GRAVITY_MASK) | gravity;
requestLayout();
}
}
@android.view.RemotableViewMethod
public void setVerticalGravity(int verticalGravity) {
final int gravity = verticalGravity & Gravity.VERTICAL_GRAVITY_MASK;
if ((mGravity & Gravity.VERTICAL_GRAVITY_MASK) != gravity) {
mGravity = (mGravity & ~Gravity.VERTICAL_GRAVITY_MASK) | gravity;
requestLayout();
}
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
return new LinearLayout.LayoutParams(getContext(), attrs);
}
/**
* Returns a set of layout parameters with a width of
* {@link android.view.ViewGroup.LayoutParams#MATCH_PARENT}
* and a height of {@link android.view.ViewGroup.LayoutParams#WRAP_CONTENT}
* when the layout's orientation is {@link #VERTICAL}. When the orientation is
* {@link #HORIZONTAL}, the width is set to {@link LayoutParams#WRAP_CONTENT}
* and the height to {@link LayoutParams#WRAP_CONTENT}.
*/
@Override
protected LayoutParams generateDefaultLayoutParams() {
if (mOrientation == HORIZONTAL) {
return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
} else if (mOrientation == VERTICAL) {
return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
}
return null;
}
@Override
protected LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
return new LayoutParams(p);
}
// Override to allow type-checking of LayoutParams.
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LinearLayout.LayoutParams;
}
/**
* Per-child layout information associated with ViewLinearLayout.
*
* @attr ref android.R.styleable#LinearLayout_Layout_layout_weight
* @attr ref android.R.styleable#LinearLayout_Layout_layout_gravity
*/
public static class LayoutParams extends ViewGroup.MarginLayoutParams {
/**
* Indicates how much of the extra space in the LinearLayout will be
* allocated to the view associated with these LayoutParams. Specify
* 0 if the view should not be stretched. Otherwise the extra pixels
* will be pro-rated among all views whose weight is greater than 0.
*/
@ViewDebug.ExportedProperty
public float weight;
/**
* Gravity for the view associated with these LayoutParams.
*
* @see android.view.Gravity
*/
@ViewDebug.ExportedProperty(mapping = {
@ViewDebug.IntToString(from = -1, to = "NONE"),
@ViewDebug.IntToString(from = Gravity.NO_GRAVITY, to = "NONE"),
@ViewDebug.IntToString(from = Gravity.TOP, to = "TOP"),
@ViewDebug.IntToString(from = Gravity.BOTTOM, to = "BOTTOM"),
@ViewDebug.IntToString(from = Gravity.LEFT, to = "LEFT"),
@ViewDebug.IntToString(from = Gravity.RIGHT, to = "RIGHT"),
@ViewDebug.IntToString(from = Gravity.CENTER_VERTICAL, to = "CENTER_VERTICAL"),
@ViewDebug.IntToString(from = Gravity.FILL_VERTICAL, to = "FILL_VERTICAL"),
@ViewDebug.IntToString(from = Gravity.CENTER_HORIZONTAL, to = "CENTER_HORIZONTAL"),
@ViewDebug.IntToString(from = Gravity.FILL_HORIZONTAL, to = "FILL_HORIZONTAL"),
@ViewDebug.IntToString(from = Gravity.CENTER, to = "CENTER"),
@ViewDebug.IntToString(from = Gravity.FILL, to = "FILL")
})
public int gravity = -1;
/**
* {@inheritDoc}
*/
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
TypedArray a =
c.obtainStyledAttributes(attrs, com.android.internal.R.styleable.LinearLayout_Layout);
weight = a.getFloat(com.android.internal.R.styleable.LinearLayout_Layout_layout_weight, 0);
gravity = a.getInt(com.android.internal.R.styleable.LinearLayout_Layout_layout_gravity, -1);
a.recycle();
}
/**
* {@inheritDoc}
*/
public LayoutParams(int width, int height) {
super(width, height);
weight = 0;
}
/**
* Creates a new set of layout parameters with the specified width, height
* and weight.
*
* @param width the width, either {@link #MATCH_PARENT},
* {@link #WRAP_CONTENT} or a fixed size in pixels
* @param height the height, either {@link #MATCH_PARENT},
* {@link #WRAP_CONTENT} or a fixed size in pixels
* @param weight the weight
*/
public LayoutParams(int width, int height, float weight) {
super(width, height);
this.weight = weight;
}
/**
* {@inheritDoc}
*/
public LayoutParams(ViewGroup.LayoutParams p) {
super(p);
}
/**
* {@inheritDoc}
*/
public LayoutParams(MarginLayoutParams source) {
super(source);
}
@Override
public String debug(String output) {
return output + "LinearLayout.LayoutParams={width=" + sizeToString(width) +
", height=" + sizeToString(height) + " weight=" + weight + "}";
}
}
}
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