The Tor Browser: mobile/android/base/gfx/ScrollbarLayer.java@b8a032363ba2 (annotated)

mobile/android/base/gfx/ScrollbarLayer.java@b8a032363ba2 (annotated)

mobile/android/base/gfx/ScrollbarLayer.java

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko.gfx;
 import org.mozilla.gecko.util.FloatUtils;
 import android.graphics.Bitmap;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import android.opengl.GLES20;
 import java.nio.FloatBuffer;
 public class ScrollbarLayer extends TileLayer {
     public static final long FADE_DELAY = 500; // milliseconds before fade-out starts
     private static final float FADE_AMOUNT = 0.03f; // how much (as a percent) the scrollbar should fade per frame
     private final boolean mVertical;
     private float mOpacity;
     // To avoid excessive GC, declare some objects here that would otherwise
     // be created and destroyed frequently during draw().
     private final RectF mBarRectF;
     private final Rect mBarRect;
     private final float[] mCoords;
     private final RectF mCapRectF;
     private LayerRenderer mRenderer;
     private int mProgram;
     private int mPositionHandle;
     private int mTextureHandle;
     private int mSampleHandle;
     private int mTMatrixHandle;
     private int mOpacityHandle;
     // Fragment shader used to draw the scroll-bar with opacity
     private static final String FRAGMENT_SHADER =
         "precision mediump float;\n" +
         "varying vec2 vTexCoord;\n" +
         "uniform sampler2D sTexture;\n" +
         "uniform float uOpacity;\n" +
         "void main() {\n" +
         "    gl_FragColor = texture2D(sTexture, vTexCoord);\n" +
         "    gl_FragColor.a *= uOpacity;\n" +
         "}\n";
     // Dimensions of the texture bitmap (will always be power-of-two)
     private final int mTexWidth;
     private final int mTexHeight;
     // Some useful dimensions of the actual content in the bitmap
     private final int mBarWidth;
     private final int mCapLength;
     private final Rect mStartCapTexCoords;  // top/left endcap coordinates
     private final Rect mBodyTexCoords;      // 1-pixel slice of the texture to be stretched
     private final Rect mEndCapTexCoords;    // bottom/right endcap coordinates
     ScrollbarLayer(LayerRenderer renderer, Bitmap scrollbarImage, IntSize imageSize, boolean vertical) {
         super(new BufferedCairoImage(scrollbarImage), TileLayer.PaintMode.NORMAL);
         mRenderer = renderer;
         mVertical = vertical;
         mBarRectF = new RectF();
         mBarRect = new Rect();
         mCoords = new float[20];
         mCapRectF = new RectF();
         mTexHeight = scrollbarImage.getHeight();
         mTexWidth = scrollbarImage.getWidth();
         if (mVertical) {
             mBarWidth = imageSize.width;
             mCapLength = imageSize.height / 2;
             mStartCapTexCoords = new Rect(0, mTexHeight - mCapLength, imageSize.width, mTexHeight);
             mBodyTexCoords = new Rect(0, mTexHeight - (mCapLength + 1), imageSize.width, mTexHeight - mCapLength);
             mEndCapTexCoords = new Rect(0, mTexHeight - imageSize.height, imageSize.width, mTexHeight - (mCapLength + 1));
         } else {
             mBarWidth = imageSize.height;
             mCapLength = imageSize.width / 2;
             mStartCapTexCoords = new Rect(0, mTexHeight - imageSize.height, mCapLength, mTexHeight);
             mBodyTexCoords = new Rect(mCapLength, mTexHeight - imageSize.height, mCapLength + 1, mTexHeight);
             mEndCapTexCoords = new Rect(mCapLength + 1, mTexHeight - imageSize.height, imageSize.width, mTexHeight);
         }
     }
     private void createProgram() {
         int vertexShader = LayerRenderer.loadShader(GLES20.GL_VERTEX_SHADER,
                                                     LayerRenderer.DEFAULT_VERTEX_SHADER);
         int fragmentShader = LayerRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER,
                                                       FRAGMENT_SHADER);
         mProgram = GLES20.glCreateProgram();
         GLES20.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program
         GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
         GLES20.glLinkProgram(mProgram);                  // creates OpenGL program executables
         // Get handles to the shaders' vPosition, aTexCoord, sTexture, and uTMatrix members.
         mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
         mTextureHandle = GLES20.glGetAttribLocation(mProgram, "aTexCoord");
         mSampleHandle = GLES20.glGetUniformLocation(mProgram, "sTexture");
         mTMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uTMatrix");
         mOpacityHandle = GLES20.glGetUniformLocation(mProgram, "uOpacity");
     }
     private void activateProgram() {
         // Add the program to the OpenGL environment
         GLES20.glUseProgram(mProgram);
         // Set the transformation matrix
         GLES20.glUniformMatrix4fv(mTMatrixHandle, 1, false,
                                   LayerRenderer.DEFAULT_TEXTURE_MATRIX, 0);
         // Enable the arrays from which we get the vertex and texture coordinates
         GLES20.glEnableVertexAttribArray(mPositionHandle);
         GLES20.glEnableVertexAttribArray(mTextureHandle);
         GLES20.glUniform1i(mSampleHandle, 0);
         GLES20.glUniform1f(mOpacityHandle, mOpacity);
     }
     private void deactivateProgram() {
         GLES20.glDisableVertexAttribArray(mTextureHandle);
         GLES20.glDisableVertexAttribArray(mPositionHandle);
         GLES20.glUseProgram(0);
     }
     /**
      * Decrease the opacity of the scrollbar by one frame's worth.
      * Return true if the opacity was decreased, or false if the scrollbars
      * are already fully faded out.
      */
     public boolean fade() {
         if (FloatUtils.fuzzyEquals(mOpacity, 0.0f)) {
             return false;
         }
         beginTransaction(); // called on compositor thread
         mOpacity = Math.max(mOpacity - FADE_AMOUNT, 0.0f);
         endTransaction();
         return true;
     }
     /**
      * Restore the opacity of the scrollbar to fully opaque.
      * Return true if the opacity was changed, or false if the scrollbars
      * are already fully opaque.
      */
     public boolean unfade() {
         if (FloatUtils.fuzzyEquals(mOpacity, 1.0f)) {
             return false;
         }
         beginTransaction(); // called on compositor thread
         mOpacity = 1.0f;
         endTransaction();
         return true;
     }
     @Override
     public void draw(RenderContext context) {
         if (!initialized())
             return;
         // Create the shader program, if necessary
         if (mProgram == 0) {
             createProgram();
         }
         // Enable the shader program
         mRenderer.deactivateDefaultProgram();
         activateProgram();
         GLES20.glEnable(GLES20.GL_BLEND);
         GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
         if (mVertical) {
             getVerticalRect(context, mBarRectF);
         } else {
             getHorizontalRect(context, mBarRectF);
         }
         RectUtils.round(mBarRectF, mBarRect);
         GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
         GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, getTextureID());
         float viewWidth = context.viewport.width();
         float viewHeight = context.viewport.height();
         mBarRectF.set(mBarRect.left, viewHeight - mBarRect.top, mBarRect.right, viewHeight - mBarRect.bottom);
         mBarRectF.offset(context.offset.x, -context.offset.y);
         // We take a 1-pixel slice from the center of the image and scale it to become the bar
         fillRectCoordBuffer(mCoords, mBarRectF, viewWidth, viewHeight, mBodyTexCoords, mTexWidth, mTexHeight);
         // Get the buffer and handles from the context
         FloatBuffer coordBuffer = context.coordBuffer;
         int positionHandle = mPositionHandle;
         int textureHandle = mTextureHandle;
         // Make sure we are at position zero in the buffer in case other draw methods did not
         // clean up after themselves
         coordBuffer.position(0);
         coordBuffer.put(mCoords);
         // Unbind any the current array buffer so we can use client side buffers
         GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
         // Vertex coordinates are x,y,z starting at position 0 into the buffer.
         coordBuffer.position(0);
         GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 20, coordBuffer);
         // Texture coordinates are texture_x, texture_y starting at position 3 into the buffer.
         coordBuffer.position(3);
         GLES20.glVertexAttribPointer(textureHandle, 2, GLES20.GL_FLOAT, false, 20, coordBuffer);
         GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
         // Reset the position in the buffer for the next set of vertex and texture coordinates.
         coordBuffer.position(0);
         if (mVertical) {
             // top endcap
             mCapRectF.set(mBarRectF.left, mBarRectF.top + mCapLength, mBarRectF.right, mBarRectF.top);
         } else {
             // left endcap
             mCapRectF.set(mBarRectF.left - mCapLength, mBarRectF.bottom + mBarWidth, mBarRectF.left, mBarRectF.bottom);
         }
         fillRectCoordBuffer(mCoords, mCapRectF, viewWidth, viewHeight, mStartCapTexCoords, mTexWidth, mTexHeight);
         coordBuffer.put(mCoords);
         // Vertex coordinates are x,y,z starting at position 0 into the buffer.
         coordBuffer.position(0);
         GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 20, coordBuffer);
         // Texture coordinates are texture_x, texture_y starting at position 3 into the buffer.
         coordBuffer.position(3);
         GLES20.glVertexAttribPointer(textureHandle, 2, GLES20.GL_FLOAT, false, 20, coordBuffer);
         GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
         // Reset the position in the buffer for the next set of vertex and texture coordinates.
         coordBuffer.position(0);
         if (mVertical) {
             // bottom endcap
             mCapRectF.set(mBarRectF.left, mBarRectF.bottom, mBarRectF.right, mBarRectF.bottom - mCapLength);
         } else {
             // right endcap
             mCapRectF.set(mBarRectF.right, mBarRectF.bottom + mBarWidth, mBarRectF.right + mCapLength, mBarRectF.bottom);
         }
         fillRectCoordBuffer(mCoords, mCapRectF, viewWidth, viewHeight, mEndCapTexCoords, mTexWidth, mTexHeight);
         coordBuffer.put(mCoords);
         // Vertex coordinates are x,y,z starting at position 0 into the buffer.
         coordBuffer.position(0);
         GLES20.glVertexAttribPointer(positionHandle, 3, GLES20.GL_FLOAT, false, 20, coordBuffer);
         // Texture coordinates are texture_x, texture_y starting at position 3 into the buffer.
         coordBuffer.position(3);
         GLES20.glVertexAttribPointer(textureHandle, 2, GLES20.GL_FLOAT, false, 20, coordBuffer);
         GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
         // Reset the position in the buffer for the next set of vertex and texture coordinates.
         coordBuffer.position(0);
         // Enable the default shader program again
         deactivateProgram();
         mRenderer.activateDefaultProgram();
     }
     private void getVerticalRect(RenderContext context, RectF dest) {
         RectF viewport = context.viewport;
         RectF pageRect = context.pageRect;
         float viewportHeight = viewport.height() - context.offset.y;
         float barStart = ((viewport.top - context.offset.y - pageRect.top) * (viewportHeight / pageRect.height())) + mCapLength;
         float barEnd = ((viewport.bottom - context.offset.y - pageRect.top) * (viewportHeight / pageRect.height())) - mCapLength;
         if (barStart > barEnd) {
             float middle = (barStart + barEnd) / 2.0f;
             barStart = barEnd = middle;
         }
         dest.set(viewport.width() - mBarWidth, barStart, viewport.width(), barEnd);
     }
     private void getHorizontalRect(RenderContext context, RectF dest) {
         RectF viewport = context.viewport;
         RectF pageRect = context.pageRect;
         float viewportWidth = viewport.width() - context.offset.x;
         float barStart = ((viewport.left - context.offset.x - pageRect.left) * (viewport.width() / pageRect.width())) + mCapLength;
         float barEnd = ((viewport.right - context.offset.x - pageRect.left) * (viewport.width() / pageRect.width())) - mCapLength;
         if (barStart > barEnd) {
             float middle = (barStart + barEnd) / 2.0f;
             barStart = barEnd = middle;
         }
         dest.set(barStart, viewport.height() - mBarWidth, barEnd, viewport.height());
     }
 }

The Tor Browser / annotate

mobile/android/base/gfx/ScrollbarLayer.java@b8a032363ba2 (annotated)

mobile/android/base/gfx/ScrollbarLayer.java