Android example source code file (ShapeDrawable.java)

This example Android source code file (ShapeDrawable.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, clonenotsupportedexception, constantstate, content, drawing, graphics, io, override, paint, rect, resources, shaderfactory, shapedrawable, shapestate, string, typedarray, ui, unknown, xmlpullparser

The ShapeDrawable.java Android example source code

/*
 * Copyright (C) 2007 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.graphics.drawable;

import android.graphics.*;
import android.graphics.drawable.shapes.Shape;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.util.AttributeSet;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import java.io.IOException;

/**
 * A Drawable object that draws primitive shapes. 
 * A ShapeDrawable takes a {@link android.graphics.drawable.shapes.Shape}
 * object and manages its presence on the screen. If no Shape is given, then
 * the ShapeDrawable will default to a 
 * {@link android.graphics.drawable.shapes.RectShape}.
 *
 * @attr ref android.R.styleable#ShapeDrawablePadding_left
 * @attr ref android.R.styleable#ShapeDrawablePadding_top
 * @attr ref android.R.styleable#ShapeDrawablePadding_right
 * @attr ref android.R.styleable#ShapeDrawablePadding_bottom
 * @attr ref android.R.styleable#ShapeDrawable_color
 * @attr ref android.R.styleable#ShapeDrawable_width
 * @attr ref android.R.styleable#ShapeDrawable_height
 */
public class ShapeDrawable extends Drawable {
    private ShapeState mShapeState;
    private boolean mMutated;

    /**
     * ShapeDrawable constructor.
     */
    public ShapeDrawable() {
        this((ShapeState) null);
    }
    
    /**
     * Creates a ShapeDrawable with a specified Shape.
     * 
     * @param s the Shape that this ShapeDrawable should be
     */
    public ShapeDrawable(Shape s) {
        this((ShapeState) null);
        
        mShapeState.mShape = s;
    }
    
    private ShapeDrawable(ShapeState state) {
        mShapeState = new ShapeState(state);
    }

    /**
     * Returns the Shape of this ShapeDrawable.
     */
    public Shape getShape() {
        return mShapeState.mShape;
    }
    
    /**
     * Sets the Shape of this ShapeDrawable.
     */
    public void setShape(Shape s) {
        mShapeState.mShape = s;
        updateShape();
    }
    
    /**
     * Sets a ShaderFactory to which requests for a 
     * {@link android.graphics.Shader} object will be made.
     * 
     * @param fact an instance of your ShaderFactory implementation
     */
    public void setShaderFactory(ShaderFactory fact) {
        mShapeState.mShaderFactory = fact;
    }
    
    /**
     * Returns the ShaderFactory used by this ShapeDrawable for requesting a 
     * {@link android.graphics.Shader}.
     */
    public ShaderFactory getShaderFactory() {
        return mShapeState.mShaderFactory;
    }

    /**
     * Returns the Paint used to draw the shape.
     */
    public Paint getPaint() {
        return mShapeState.mPaint;
    }
    
    /**
     * Sets padding for the shape.
     * 
     * @param left    padding for the left side (in pixels)
     * @param top     padding for the top (in pixels)
     * @param right   padding for the right side (in pixels)
     * @param bottom  padding for the bottom (in pixels)
     */
    public void setPadding(int left, int top, int right, int bottom) {
        if ((left | top | right | bottom) == 0) {
            mShapeState.mPadding = null;
        } else {
            if (mShapeState.mPadding == null) {
                mShapeState.mPadding = new Rect();
            }
            mShapeState.mPadding.set(left, top, right, bottom);
        }
    }
    
    /**
     * Sets padding for this shape, defined by a Rect object.
     * Define the padding in the Rect object as: left, top, right, bottom.
     */
    public void setPadding(Rect padding) {
        if (padding == null) {
            mShapeState.mPadding = null;
        } else {
            if (mShapeState.mPadding == null) {
                mShapeState.mPadding = new Rect();
            }
            mShapeState.mPadding.set(padding);
        }
    }
    
    /**
     * Sets the intrinsic (default) width for this shape.
     * 
     * @param width the intrinsic width (in pixels)
     */
    public void setIntrinsicWidth(int width) {
        mShapeState.mIntrinsicWidth = width;
    }
    
    /**
     * Sets the intrinsic (default) height for this shape.
     * 
     * @param height the intrinsic height (in pixels)
     */
    public void setIntrinsicHeight(int height) {
        mShapeState.mIntrinsicHeight = height;
    }
    
    @Override
    public int getIntrinsicWidth() {
        return mShapeState.mIntrinsicWidth;
    }
    
    @Override
    public int getIntrinsicHeight() {
        return mShapeState.mIntrinsicHeight;
    }
    
    @Override
    public boolean getPadding(Rect padding) {
        if (mShapeState.mPadding != null) {
            padding.set(mShapeState.mPadding);
            return true;
        } else {
            return super.getPadding(padding);
        }
    }

    private static int modulateAlpha(int paintAlpha, int alpha) {
        int scale = alpha + (alpha >>> 7);  // convert to 0..256
        return paintAlpha * scale >>> 8;
    }

    /**
     * Called from the drawable's draw() method after the canvas has been set
     * to draw the shape at (0,0). Subclasses can override for special effects
     * such as multiple layers, stroking, etc.
     */
    protected void onDraw(Shape shape, Canvas canvas, Paint paint) {
        shape.draw(canvas, paint);
    }

    @Override
    public void draw(Canvas canvas) {
        Rect r = getBounds();
        Paint paint = mShapeState.mPaint;

        int prevAlpha = paint.getAlpha();
        paint.setAlpha(modulateAlpha(prevAlpha, mShapeState.mAlpha));

        if (mShapeState.mShape != null) {
            // need the save both for the translate, and for the (unknown) Shape
            int count = canvas.save();
            canvas.translate(r.left, r.top);
            onDraw(mShapeState.mShape, canvas, paint);
            canvas.restoreToCount(count);
        } else {
            canvas.drawRect(r, paint);
        }
        
        // restore
        paint.setAlpha(prevAlpha);
    }

    @Override
    public int getChangingConfigurations() {
        return super.getChangingConfigurations()
                | mShapeState.mChangingConfigurations;
    }
    
    /**
     * Set the alpha level for this drawable [0..255]. Note that this drawable
     * also has a color in its paint, which has an alpha as well. These two
     * values are automatically combined during drawing. Thus if the color's
     * alpha is 75% (i.e. 192) and the drawable's alpha is 50% (i.e. 128), then
     * the combined alpha that will be used during drawing will be 37.5%
     * (i.e. 96).
     */
    @Override public void setAlpha(int alpha) {
        mShapeState.mAlpha = alpha;
    }
    
    @Override
    public void setColorFilter(ColorFilter cf) {
        mShapeState.mPaint.setColorFilter(cf);
    }
    
    @Override
    public int getOpacity() {
        if (mShapeState.mShape == null) {
            final Paint p = mShapeState.mPaint;
            if (p.getXfermode() == null) {
                final int alpha = p.getAlpha();
                if (alpha == 0) {
                    return PixelFormat.TRANSPARENT;
                }
                if (alpha == 255) {
                    return PixelFormat.OPAQUE;
                }
            }
        }
        // not sure, so be safe
        return PixelFormat.TRANSLUCENT;
    }

    @Override
    public void setDither(boolean dither) {
        mShapeState.mPaint.setDither(dither);
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);
        updateShape();
    }

    /**
     * Subclasses override this to parse custom subelements.
     * If you handle it, return true, else return <em>super.inflateTag(...).
     */
    protected boolean inflateTag(String name, Resources r, XmlPullParser parser,
            AttributeSet attrs) {

        if (name.equals("padding")) {
            TypedArray a = r.obtainAttributes(attrs,
                    com.android.internal.R.styleable.ShapeDrawablePadding);
            setPadding(
                    a.getDimensionPixelOffset(
                            com.android.internal.R.styleable.ShapeDrawablePadding_left, 0),
                    a.getDimensionPixelOffset(
                            com.android.internal.R.styleable.ShapeDrawablePadding_top, 0),
                    a.getDimensionPixelOffset(
                            com.android.internal.R.styleable.ShapeDrawablePadding_right, 0),
                    a.getDimensionPixelOffset(
                            com.android.internal.R.styleable.ShapeDrawablePadding_bottom, 0));
            a.recycle();
            return true;
        }

        return false;
    }

    @Override
    public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
                        throws XmlPullParserException, IOException {
        super.inflate(r, parser, attrs);

        TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.ShapeDrawable);

        int color = mShapeState.mPaint.getColor();
        color = a.getColor(com.android.internal.R.styleable.ShapeDrawable_color, color);
        mShapeState.mPaint.setColor(color);
            
        setIntrinsicWidth((int)
                a.getDimension(com.android.internal.R.styleable.ShapeDrawable_width, 0f));
        setIntrinsicHeight((int)
                a.getDimension(com.android.internal.R.styleable.ShapeDrawable_height, 0f));

        a.recycle();

        int type;
        final int outerDepth = parser.getDepth();
        while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
               && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
            if (type != XmlPullParser.START_TAG) {
                continue;
            }
            
            final String name = parser.getName();
            // call our subclass
            if (!inflateTag(name, r, parser, attrs)) {
                android.util.Log.w("drawable", "Unknown element: " + name +
                        " for ShapeDrawable " + this);
            }
        }
    }

    private void updateShape() {
        if (mShapeState.mShape != null) {
            final Rect r = getBounds();
            final int w = r.width();
            final int h = r.height();

            mShapeState.mShape.resize(w, h);
            if (mShapeState.mShaderFactory != null) {
                mShapeState.mPaint.setShader(mShapeState.mShaderFactory.resize(w, h));
            }
        }
    }
    
    @Override
    public ConstantState getConstantState() {
        mShapeState.mChangingConfigurations = super.getChangingConfigurations();
        return mShapeState;
    }

    @Override
    public Drawable mutate() {
        if (!mMutated && super.mutate() == this) {
            mShapeState.mPaint = new Paint(mShapeState.mPaint);
            mShapeState.mPadding = new Rect(mShapeState.mPadding);
            try {
                mShapeState.mShape = mShapeState.mShape.clone();
            } catch (CloneNotSupportedException e) {
                return null;
            }
            mMutated = true;
        }
        return this;
    }

    /**
     * Defines the intrinsic properties of this ShapeDrawable's Shape.
     */
    final static class ShapeState extends ConstantState {
        int mChangingConfigurations;
        Paint mPaint;
        Shape mShape;
        Rect mPadding;
        int mIntrinsicWidth;
        int mIntrinsicHeight;
        int mAlpha = 255;
        ShaderFactory mShaderFactory;
        
        ShapeState(ShapeState orig) {
            if (orig != null) {
                mPaint = orig.mPaint;
                mShape = orig.mShape;
                mPadding = orig.mPadding;
                mIntrinsicWidth = orig.mIntrinsicWidth;
                mIntrinsicHeight = orig.mIntrinsicHeight;
                mAlpha = orig.mAlpha;
                mShaderFactory = orig.mShaderFactory;
            } else {
                mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            }
        }
        
        @Override
        public Drawable newDrawable() {
            return new ShapeDrawable(this);
        }
        
        @Override
        public Drawable newDrawable(Resources res) {
            return new ShapeDrawable(this);
        }
        
        @Override
        public int getChangingConfigurations() {
            return mChangingConfigurations;
        }
    }
    
    /**
     * Base class defines a factory object that is called each time the drawable
     * is resized (has a new width or height). Its resize() method returns a
     * corresponding shader, or null.
     * Implement this class if you'd like your ShapeDrawable to use a special
     * {@link android.graphics.Shader}, such as a 
     * {@link android.graphics.LinearGradient}. 
     * 
     */
    public static abstract class ShaderFactory {
        /**
         * Returns the Shader to be drawn when a Drawable is drawn.
         * The dimensions of the Drawable are passed because they may be needed
         * to adjust how the Shader is configured for drawing.
         * This is called by ShapeDrawable.setShape().
         * 
         * @param width  the width of the Drawable being drawn
         * @param height the heigh of the Drawable being drawn
         * @return       the Shader to be drawn
         */
        public abstract Shader resize(int width, int height);
    }
    
    // other subclass could wack the Shader's localmatrix based on the
    // resize params (e.g. scaletofit, etc.). This could be used to scale
    // a bitmap to fill the bounds without needing any other special casing.
}