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Diffstat (limited to 'src/com/android/gallery3d/ui/EdgeEffect.java')
| -rw-r--r-- | src/com/android/gallery3d/ui/EdgeEffect.java | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/ui/EdgeEffect.java b/src/com/android/gallery3d/ui/EdgeEffect.java new file mode 100644 index 000000000..87ff0c5d3 --- /dev/null +++ b/src/com/android/gallery3d/ui/EdgeEffect.java @@ -0,0 +1,443 @@ +/* + * Copyright (C) 2011 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 com.android.gallery3d.ui; + +import android.content.Context; +import android.graphics.Canvas; +import android.graphics.Rect; +import android.view.animation.DecelerateInterpolator; +import android.view.animation.Interpolator; + +import com.android.gallery3d.R; +import com.android.gallery3d.glrenderer.GLCanvas; +import com.android.gallery3d.glrenderer.ResourceTexture; + +// This is copied from android.widget.EdgeEffect with some small modifications: +// (1) Copy the images (overscroll_{edge|glow}.png) to local resources. +// (2) Use "GLCanvas" instead of "Canvas" for draw()'s parameter. +// (3) Use a private Drawable class (which inherits from ResourceTexture) +// instead of android.graphics.drawable.Drawable to hold the images. +// The private Drawable class is used to translate original Canvas calls to +// corresponding GLCanvas calls. + +/** + * This class performs the graphical effect used at the edges of scrollable widgets + * when the user scrolls beyond the content bounds in 2D space. + * + * <p>EdgeEffect is stateful. Custom widgets using EdgeEffect should create an + * instance for each edge that should show the effect, feed it input data using + * the methods {@link #onAbsorb(int)}, {@link #onPull(float)}, and {@link #onRelease()}, + * and draw the effect using {@link #draw(Canvas)} in the widget's overridden + * {@link android.view.View#draw(Canvas)} method. If {@link #isFinished()} returns + * false after drawing, the edge effect's animation is not yet complete and the widget + * should schedule another drawing pass to continue the animation.</p> + * + * <p>When drawing, widgets should draw their main content and child views first, + * usually by invoking <code>super.draw(canvas)</code> from an overridden <code>draw</code> + * method. (This will invoke onDraw and dispatch drawing to child views as needed.) + * The edge effect may then be drawn on top of the view's content using the + * {@link #draw(Canvas)} method.</p> + */ +public class EdgeEffect { + @SuppressWarnings("unused") + private static final String TAG = "EdgeEffect"; + + // Time it will take the effect to fully recede in ms + private static final int RECEDE_TIME = 1000; + + // Time it will take before a pulled glow begins receding in ms + private static final int PULL_TIME = 167; + + // Time it will take in ms for a pulled glow to decay to partial strength before release + private static final int PULL_DECAY_TIME = 1000; + + private static final float MAX_ALPHA = 0.8f; + private static final float HELD_EDGE_ALPHA = 0.7f; + private static final float HELD_EDGE_SCALE_Y = 0.5f; + private static final float HELD_GLOW_ALPHA = 0.5f; + private static final float HELD_GLOW_SCALE_Y = 0.5f; + + private static final float MAX_GLOW_HEIGHT = 4.f; + + private static final float PULL_GLOW_BEGIN = 1.f; + private static final float PULL_EDGE_BEGIN = 0.6f; + + // Minimum velocity that will be absorbed + private static final int MIN_VELOCITY = 100; + + private static final float EPSILON = 0.001f; + + private final Drawable mEdge; + private final Drawable mGlow; + private int mWidth; + private int mHeight; + private final int MIN_WIDTH = 300; + private final int mMinWidth; + + private float mEdgeAlpha; + private float mEdgeScaleY; + private float mGlowAlpha; + private float mGlowScaleY; + + private float mEdgeAlphaStart; + private float mEdgeAlphaFinish; + private float mEdgeScaleYStart; + private float mEdgeScaleYFinish; + private float mGlowAlphaStart; + private float mGlowAlphaFinish; + private float mGlowScaleYStart; + private float mGlowScaleYFinish; + + private long mStartTime; + private float mDuration; + + private final Interpolator mInterpolator; + + private static final int STATE_IDLE = 0; + private static final int STATE_PULL = 1; + private static final int STATE_ABSORB = 2; + private static final int STATE_RECEDE = 3; + private static final int STATE_PULL_DECAY = 4; + + // How much dragging should effect the height of the edge image. + // Number determined by user testing. + private static final int PULL_DISTANCE_EDGE_FACTOR = 7; + + // How much dragging should effect the height of the glow image. + // Number determined by user testing. + private static final int PULL_DISTANCE_GLOW_FACTOR = 7; + private static final float PULL_DISTANCE_ALPHA_GLOW_FACTOR = 1.1f; + + private static final int VELOCITY_EDGE_FACTOR = 8; + private static final int VELOCITY_GLOW_FACTOR = 16; + + private int mState = STATE_IDLE; + + private float mPullDistance; + + /** + * Construct a new EdgeEffect with a theme appropriate for the provided context. + * @param context Context used to provide theming and resource information for the EdgeEffect + */ + public EdgeEffect(Context context) { + mEdge = new Drawable(context, R.drawable.overscroll_edge); + mGlow = new Drawable(context, R.drawable.overscroll_glow); + + mMinWidth = (int) (context.getResources().getDisplayMetrics().density * MIN_WIDTH + 0.5f); + mInterpolator = new DecelerateInterpolator(); + } + + /** + * Set the size of this edge effect in pixels. + * + * @param width Effect width in pixels + * @param height Effect height in pixels + */ + public void setSize(int width, int height) { + mWidth = width; + mHeight = height; + } + + /** + * Reports if this EdgeEffect's animation is finished. If this method returns false + * after a call to {@link #draw(Canvas)} the host widget should schedule another + * drawing pass to continue the animation. + * + * @return true if animation is finished, false if drawing should continue on the next frame. + */ + public boolean isFinished() { + return mState == STATE_IDLE; + } + + /** + * Immediately finish the current animation. + * After this call {@link #isFinished()} will return true. + */ + public void finish() { + mState = STATE_IDLE; + } + + /** + * A view should call this when content is pulled away from an edge by the user. + * This will update the state of the current visual effect and its associated animation. + * The host view should always {@link android.view.View#invalidate()} after this + * and draw the results accordingly. + * + * @param deltaDistance Change in distance since the last call. Values may be 0 (no change) to + * 1.f (full length of the view) or negative values to express change + * back toward the edge reached to initiate the effect. + */ + public void onPull(float deltaDistance) { + final long now = AnimationTime.get(); + if (mState == STATE_PULL_DECAY && now - mStartTime < mDuration) { + return; + } + if (mState != STATE_PULL) { + mGlowScaleY = PULL_GLOW_BEGIN; + } + mState = STATE_PULL; + + mStartTime = now; + mDuration = PULL_TIME; + + mPullDistance += deltaDistance; + float distance = Math.abs(mPullDistance); + + mEdgeAlpha = mEdgeAlphaStart = Math.max(PULL_EDGE_BEGIN, Math.min(distance, MAX_ALPHA)); + mEdgeScaleY = mEdgeScaleYStart = Math.max( + HELD_EDGE_SCALE_Y, Math.min(distance * PULL_DISTANCE_EDGE_FACTOR, 1.f)); + + mGlowAlpha = mGlowAlphaStart = Math.min(MAX_ALPHA, + mGlowAlpha + + (Math.abs(deltaDistance) * PULL_DISTANCE_ALPHA_GLOW_FACTOR)); + + float glowChange = Math.abs(deltaDistance); + if (deltaDistance > 0 && mPullDistance < 0) { + glowChange = -glowChange; + } + if (mPullDistance == 0) { + mGlowScaleY = 0; + } + + // Do not allow glow to get larger than MAX_GLOW_HEIGHT. + mGlowScaleY = mGlowScaleYStart = Math.min(MAX_GLOW_HEIGHT, Math.max( + 0, mGlowScaleY + glowChange * PULL_DISTANCE_GLOW_FACTOR)); + + mEdgeAlphaFinish = mEdgeAlpha; + mEdgeScaleYFinish = mEdgeScaleY; + mGlowAlphaFinish = mGlowAlpha; + mGlowScaleYFinish = mGlowScaleY; + } + + /** + * Call when the object is released after being pulled. + * This will begin the "decay" phase of the effect. After calling this method + * the host view should {@link android.view.View#invalidate()} and thereby + * draw the results accordingly. + */ + public void onRelease() { + mPullDistance = 0; + + if (mState != STATE_PULL && mState != STATE_PULL_DECAY) { + return; + } + + mState = STATE_RECEDE; + mEdgeAlphaStart = mEdgeAlpha; + mEdgeScaleYStart = mEdgeScaleY; + mGlowAlphaStart = mGlowAlpha; + mGlowScaleYStart = mGlowScaleY; + + mEdgeAlphaFinish = 0.f; + mEdgeScaleYFinish = 0.f; + mGlowAlphaFinish = 0.f; + mGlowScaleYFinish = 0.f; + + mStartTime = AnimationTime.get(); + mDuration = RECEDE_TIME; + } + + /** + * Call when the effect absorbs an impact at the given velocity. + * Used when a fling reaches the scroll boundary. + * + * <p>When using a {@link android.widget.Scroller} or {@link android.widget.OverScroller}, + * the method <code>getCurrVelocity</code> will provide a reasonable approximation + * to use here.</p> + * + * @param velocity Velocity at impact in pixels per second. + */ + public void onAbsorb(int velocity) { + mState = STATE_ABSORB; + velocity = Math.max(MIN_VELOCITY, Math.abs(velocity)); + + mStartTime = AnimationTime.get(); + mDuration = 0.1f + (velocity * 0.03f); + + // The edge should always be at least partially visible, regardless + // of velocity. + mEdgeAlphaStart = 0.f; + mEdgeScaleY = mEdgeScaleYStart = 0.f; + // The glow depends more on the velocity, and therefore starts out + // nearly invisible. + mGlowAlphaStart = 0.5f; + mGlowScaleYStart = 0.f; + + // Factor the velocity by 8. Testing on device shows this works best to + // reflect the strength of the user's scrolling. + mEdgeAlphaFinish = Math.max(0, Math.min(velocity * VELOCITY_EDGE_FACTOR, 1)); + // Edge should never get larger than the size of its asset. + mEdgeScaleYFinish = Math.max( + HELD_EDGE_SCALE_Y, Math.min(velocity * VELOCITY_EDGE_FACTOR, 1.f)); + + // Growth for the size of the glow should be quadratic to properly + // respond + // to a user's scrolling speed. The faster the scrolling speed, the more + // intense the effect should be for both the size and the saturation. + mGlowScaleYFinish = Math.min(0.025f + (velocity * (velocity / 100) * 0.00015f), 1.75f); + // Alpha should change for the glow as well as size. + mGlowAlphaFinish = Math.max( + mGlowAlphaStart, Math.min(velocity * VELOCITY_GLOW_FACTOR * .00001f, MAX_ALPHA)); + } + + + /** + * Draw into the provided canvas. Assumes that the canvas has been rotated + * accordingly and the size has been set. The effect will be drawn the full + * width of X=0 to X=width, beginning from Y=0 and extending to some factor < + * 1.f of height. + * + * @param canvas Canvas to draw into + * @return true if drawing should continue beyond this frame to continue the + * animation + */ + public boolean draw(GLCanvas canvas) { + update(); + + final int edgeHeight = mEdge.getIntrinsicHeight(); + final int edgeWidth = mEdge.getIntrinsicWidth(); + final int glowHeight = mGlow.getIntrinsicHeight(); + final int glowWidth = mGlow.getIntrinsicWidth(); + + mGlow.setAlpha((int) (Math.max(0, Math.min(mGlowAlpha, 1)) * 255)); + + int glowBottom = (int) Math.min( + glowHeight * mGlowScaleY * glowHeight/ glowWidth * 0.6f, + glowHeight * MAX_GLOW_HEIGHT); + if (mWidth < mMinWidth) { + // Center the glow and clip it. + int glowLeft = (mWidth - mMinWidth)/2; + mGlow.setBounds(glowLeft, 0, mWidth - glowLeft, glowBottom); + } else { + // Stretch the glow to fit. + mGlow.setBounds(0, 0, mWidth, glowBottom); + } + + mGlow.draw(canvas); + + mEdge.setAlpha((int) (Math.max(0, Math.min(mEdgeAlpha, 1)) * 255)); + + int edgeBottom = (int) (edgeHeight * mEdgeScaleY); + if (mWidth < mMinWidth) { + // Center the edge and clip it. + int edgeLeft = (mWidth - mMinWidth)/2; + mEdge.setBounds(edgeLeft, 0, mWidth - edgeLeft, edgeBottom); + } else { + // Stretch the edge to fit. + mEdge.setBounds(0, 0, mWidth, edgeBottom); + } + mEdge.draw(canvas); + + return mState != STATE_IDLE; + } + + private void update() { + final long time = AnimationTime.get(); + final float t = Math.min((time - mStartTime) / mDuration, 1.f); + + final float interp = mInterpolator.getInterpolation(t); + + mEdgeAlpha = mEdgeAlphaStart + (mEdgeAlphaFinish - mEdgeAlphaStart) * interp; + mEdgeScaleY = mEdgeScaleYStart + (mEdgeScaleYFinish - mEdgeScaleYStart) * interp; + mGlowAlpha = mGlowAlphaStart + (mGlowAlphaFinish - mGlowAlphaStart) * interp; + mGlowScaleY = mGlowScaleYStart + (mGlowScaleYFinish - mGlowScaleYStart) * interp; + + if (t >= 1.f - EPSILON) { + switch (mState) { + case STATE_ABSORB: + mState = STATE_RECEDE; + mStartTime = AnimationTime.get(); + mDuration = RECEDE_TIME; + + mEdgeAlphaStart = mEdgeAlpha; + mEdgeScaleYStart = mEdgeScaleY; + mGlowAlphaStart = mGlowAlpha; + mGlowScaleYStart = mGlowScaleY; + + // After absorb, the glow and edge should fade to nothing. + mEdgeAlphaFinish = 0.f; + mEdgeScaleYFinish = 0.f; + mGlowAlphaFinish = 0.f; + mGlowScaleYFinish = 0.f; + break; + case STATE_PULL: + mState = STATE_PULL_DECAY; + mStartTime = AnimationTime.get(); + mDuration = PULL_DECAY_TIME; + + mEdgeAlphaStart = mEdgeAlpha; + mEdgeScaleYStart = mEdgeScaleY; + mGlowAlphaStart = mGlowAlpha; + mGlowScaleYStart = mGlowScaleY; + + // After pull, the glow and edge should fade to nothing. + mEdgeAlphaFinish = 0.f; + mEdgeScaleYFinish = 0.f; + mGlowAlphaFinish = 0.f; + mGlowScaleYFinish = 0.f; + break; + case STATE_PULL_DECAY: + // When receding, we want edge to decrease more slowly + // than the glow. + float factor = mGlowScaleYFinish != 0 ? 1 + / (mGlowScaleYFinish * mGlowScaleYFinish) + : Float.MAX_VALUE; + mEdgeScaleY = mEdgeScaleYStart + + (mEdgeScaleYFinish - mEdgeScaleYStart) * + interp * factor; + mState = STATE_RECEDE; + break; + case STATE_RECEDE: + mState = STATE_IDLE; + break; + } + } + } + + private static class Drawable extends ResourceTexture { + private Rect mBounds = new Rect(); + private int mAlpha = 255; + + public Drawable(Context context, int resId) { + super(context, resId); + } + + public int getIntrinsicWidth() { + return getWidth(); + } + + public int getIntrinsicHeight() { + return getHeight(); + } + + public void setBounds(int left, int top, int right, int bottom) { + mBounds.set(left, top, right, bottom); + } + + public void setAlpha(int alpha) { + mAlpha = alpha; + } + + public void draw(GLCanvas canvas) { + canvas.save(GLCanvas.SAVE_FLAG_ALPHA); + canvas.multiplyAlpha(mAlpha / 255.0f); + Rect b = mBounds; + draw(canvas, b.left, b.top, b.width(), b.height()); + canvas.restore(); + } + } +} |