gecko/mobile/android/base/gfx/ScrollbarLayer.java

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/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
2012-05-21 04:12:37 -07:00
* 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());
}
}