Android example source code file (ViewManager.java)

This example Android source code file (ViewManager.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, arraylist, childview, max_surface_area, max_surface_dimension, runnable, surfaceview, ui, util, view, viewmanager, webview, widget

The ViewManager.java Android example source code

/*
 * Copyright (C) 2009 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.webkit;

import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsoluteLayout;

import java.util.ArrayList;

class ViewManager {
    private final WebView mWebView;
    private final ArrayList<ChildView> mChildren = new ArrayList();
    private boolean mHidden;
    private boolean mReadyToDraw;
    private boolean mZoomInProgress = false;

    // Threshold at which a surface is prevented from further increasing in size
    private final int MAX_SURFACE_AREA;
    // GPU Limit (hard coded for now)
    private static final int MAX_SURFACE_DIMENSION = 2048;

    class ChildView {
        int x;
        int y;
        int width;
        int height;
        View mView; // generic view to show

        ChildView() {
        }

        void setBounds(int x, int y, int width, int height) {
            this.x = x;
            this.y = y;
            this.width = width;
            this.height = height;
        }

        void attachView(int x, int y, int width, int height) {
            if (mView == null) {
                return;
            }
            setBounds(x, y, width, height);

            mWebView.mPrivateHandler.post(new Runnable() {
                public void run() {
                    // This method may be called multiple times. If the view is
                    // already attached, just set the new LayoutParams,
                    // otherwise attach the view and add it to the list of
                    // children.
                    requestLayout(ChildView.this);

                    if (mView.getParent() == null) {
                        attachViewOnUIThread();
                    }
                }
            });
        }

        private void attachViewOnUIThread() {
            mWebView.addView(mView);
            mChildren.add(this);
            if (!mReadyToDraw) {
                mView.setVisibility(View.GONE);
            }
        }

        void removeView() {
            if (mView == null) {
                return;
            }
            mWebView.mPrivateHandler.post(new Runnable() {
                public void run() {
                    removeViewOnUIThread();
                }
            });
        }

        private void removeViewOnUIThread() {
            mWebView.removeView(mView);
            mChildren.remove(this);
        }
    }

    ViewManager(WebView w) {
        mWebView = w;

        int pixelArea = w.getResources().getDisplayMetrics().widthPixels *
                        w.getResources().getDisplayMetrics().heightPixels;
        /* set the threshold to be 275% larger than the screen size. The
           percentage is simply an estimation and is not based on anything but
           basic trial-and-error tests run on multiple devices.
         */
        MAX_SURFACE_AREA = (int)(pixelArea * 2.75);
    }

    ChildView createView() {
        return new ChildView();
    }

    /**
     * This should only be called from the UI thread.
     */
    private void requestLayout(ChildView v) {

        int width = mWebView.contentToViewDimension(v.width);
        int height = mWebView.contentToViewDimension(v.height);
        int x = mWebView.contentToViewX(v.x);
        int y = mWebView.contentToViewY(v.y);

        AbsoluteLayout.LayoutParams lp;
        ViewGroup.LayoutParams layoutParams = v.mView.getLayoutParams();

        if (layoutParams instanceof AbsoluteLayout.LayoutParams) {
            lp = (AbsoluteLayout.LayoutParams) layoutParams;
            lp.width = width;
            lp.height = height;
            lp.x = x;
            lp.y = y;
        } else {
            lp = new AbsoluteLayout.LayoutParams(width, height, x, y);
        }

        // apply the layout to the view
        v.mView.setLayoutParams(lp);

        if(v.mView instanceof SurfaceView) {

            final SurfaceView sView = (SurfaceView) v.mView;

            if (sView.isFixedSize() && mZoomInProgress) {
                /* If we're already fixed, and we're in a zoom, then do nothing
                   about the size. Just wait until we get called at the end of
                   the zoom session (with mZoomInProgress false) and we'll
                   fixup our size then.
                 */
                return;
            }

            /* Compute proportional fixed width/height if necessary.
             *
             * NOTE: plugins (e.g. Flash) must not explicitly fix the size of
             * their surface. The logic below will result in unexpected behavior
             * for the plugin if they attempt to fix the size of the surface.
             */
            int fixedW = width;
            int fixedH = height;
            if (fixedW > MAX_SURFACE_DIMENSION || fixedH > MAX_SURFACE_DIMENSION) {
                if (v.width > v.height) {
                    fixedW = MAX_SURFACE_DIMENSION;
                    fixedH = v.height * MAX_SURFACE_DIMENSION / v.width;
                } else {
                    fixedH = MAX_SURFACE_DIMENSION;
                    fixedW = v.width * MAX_SURFACE_DIMENSION / v.height;
                }
            }
            if (fixedW * fixedH > MAX_SURFACE_AREA) {
                float area = MAX_SURFACE_AREA;
                if (v.width > v.height) {
                    fixedW = (int)Math.sqrt(area * v.width / v.height);
                    fixedH = v.height * fixedW / v.width;
                } else {
                    fixedH = (int)Math.sqrt(area * v.height / v.width);
                    fixedW = v.width * fixedH / v.height;
                }
            }

            if (fixedW != width || fixedH != height) {
                // if we get here, either our dimensions or area (or both)
                // exeeded our max, so we had to compute fixedW and fixedH
                sView.getHolder().setFixedSize(fixedW, fixedH);
            } else if (!sView.isFixedSize() && mZoomInProgress) {
                // just freeze where we were (view size) until we're done with
                // the zoom progress
                sView.getHolder().setFixedSize(sView.getWidth(),
                                               sView.getHeight());
            } else if (sView.isFixedSize() && !mZoomInProgress) {
                /* The changing of visibility is a hack to get around a bug in
                 * the framework that causes the surface to revert to the size
                 * it was prior to being fixed before it redraws using the
                 * values currently in its layout.
                 *
                 * The surface is destroyed when it is set to invisible and then
                 * recreated at the new dimensions when it is made visible. The
                 * same destroy/create step occurs without the change in
                 * visibility, but then exhibits the behavior described in the
                 * previous paragraph.
                 */
                if (sView.getVisibility() == View.VISIBLE) {
                    sView.setVisibility(View.INVISIBLE);
                    sView.getHolder().setSizeFromLayout();
                    // setLayoutParams() only requests the layout. If we set it
                    // to VISIBLE now, it will use the old dimension to set the
                    // size. Post a message to ensure that it shows the new size.
                    mWebView.mPrivateHandler.post(new Runnable() {
                        public void run() {
                            sView.setVisibility(View.VISIBLE);
                        }
                    });
                } else {
                    sView.getHolder().setSizeFromLayout();
                }
            }
        }
    }

    void startZoom() {
        mZoomInProgress = true;
        for (ChildView v : mChildren) {
            requestLayout(v);
        }
    }

    void endZoom() {
        mZoomInProgress = false;
        for (ChildView v : mChildren) {
            requestLayout(v);
        }
    }

    void scaleAll() {
        for (ChildView v : mChildren) {
            requestLayout(v);
        }
    }

    void hideAll() {
        if (mHidden) {
            return;
        }
        for (ChildView v : mChildren) {
            v.mView.setVisibility(View.GONE);
        }
        mHidden = true;
    }

    void showAll() {
        if (!mHidden) {
            return;
        }
        for (ChildView v : mChildren) {
            v.mView.setVisibility(View.VISIBLE);
        }
        mHidden = false;
    }

    void postResetStateAll() {
        mWebView.mPrivateHandler.post(new Runnable() {
            public void run() {
                mReadyToDraw = false;
            }
        });
    }

    void postReadyToDrawAll() {
        mWebView.mPrivateHandler.post(new Runnable() {
            public void run() {
                mReadyToDraw = true;
                for (ChildView v : mChildren) {
                    v.mView.setVisibility(View.VISIBLE);
                }
            }
        });
    }

    ChildView hitTest(int contentX, int contentY) {
        if (mHidden) {
            return null;
        }
        for (ChildView v : mChildren) {
            if (v.mView.getVisibility() == View.VISIBLE) {
                if (contentX >= v.x && contentX < (v.x + v.width)
                        && contentY >= v.y && contentY < (v.y + v.height)) {
                    return v;
                }
            }
        }
        return null;
    }
}