src/com/android/gallery3d/ui/BitmapScreenNail.java

/*
 * Copyright (C) 2012 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.graphics.Bitmap;
import android.graphics.RectF;

import com.android.gallery3d.common.Utils;
import com.android.gallery3d.data.MediaItem;

// This is a ScreenNail wraps a Bitmap. There are some extra functions:
//
// - If we need to draw before the bitmap is available, we draw a rectange of
// placeholder color (gray).
//
// - When the the bitmap is available, and we have drawn the placeholder color
// before, we will do a fade-in animation.
public class BitmapScreenNail implements ScreenNail {
    private static final String TAG = "BitmapScreenNail";
    private static final int PLACEHOLDER_COLOR = 0xFF222222;
    // The duration of the fading animation in milliseconds
    private static final int DURATION = 180;

    private static final int MAX_SIDE = 640;

    // These are special values for mAnimationStartTime
    private static final long ANIMATION_NOT_NEEDED = -1;
    private static final long ANIMATION_NEEDED = -2;
    private static final long ANIMATION_DONE = -3;

    private int mWidth;
    private int mHeight;
    private Bitmap mBitmap;
    private BitmapTexture mTexture;
    private long mAnimationStartTime = ANIMATION_NOT_NEEDED;

    public BitmapScreenNail(Bitmap bitmap) {
        mWidth = bitmap.getWidth();
        mHeight = bitmap.getHeight();
        mBitmap = bitmap;
        // We create mTexture lazily, so we don't incur the cost if we don't
        // actually need it.
    }

    public BitmapScreenNail(int width, int height) {
        setSize(width, height);
    }

    private void setSize(int width, int height) {
        if (width == 0 || height == 0) {
            width = 640;
            height = 480;
        }
        float scale = Math.min(1, (float) MAX_SIDE / Math.max(width, height));
        mWidth = Math.round(scale * width);
        mHeight = Math.round(scale * height);
    }

    // Combines the two ScreenNails.
    // Returns the used one and recycle the unused one.
    public ScreenNail combine(ScreenNail other) {
        if (other == null) {
            return this;
        }

        if (!(other instanceof BitmapScreenNail)) {
            recycle();
            return other;
        }

        // Now both are BitmapScreenNail. Move over the information about width,
        // height, and Bitmap, then recycle the other.
        BitmapScreenNail newer = (BitmapScreenNail) other;
        mWidth = newer.mWidth;
        mHeight = newer.mHeight;
        if (newer.mBitmap != null) {
            if (mBitmap != null) {
                MediaItem.getThumbPool().recycle(mBitmap);
            }
            mBitmap = newer.mBitmap;
            newer.mBitmap = null;

            if (mTexture != null) {
                mTexture.recycle();
                mTexture = null;
            }
        }

        newer.recycle();
        return this;
    }

    public void updatePlaceholderSize(int width, int height) {
        if (mBitmap != null) return;
        if (width == 0 || height == 0) return;
        setSize(width, height);
    }

    @Override
    public int getWidth() {
        return mWidth;
    }

    @Override
    public int getHeight() {
        return mHeight;
    }

    @Override
    public void noDraw() {
    }

    @Override
    public void recycle() {
        if (mTexture != null) {
            mTexture.recycle();
            mTexture = null;
        }
        if (mBitmap != null) {
            MediaItem.getThumbPool().recycle(mBitmap);
            mBitmap = null;
        }
    }

    @Override
    public void draw(GLCanvas canvas, int x, int y, int width, int height) {
        if (mBitmap == null) {
            if (mAnimationStartTime == ANIMATION_NOT_NEEDED) {
                mAnimationStartTime = ANIMATION_NEEDED;
            }
            canvas.fillRect(x, y, width, height, PLACEHOLDER_COLOR);
            return;
        }

        if (mTexture == null) {
            mTexture = new BitmapTexture(mBitmap);
        }

        if (mAnimationStartTime == ANIMATION_NEEDED) {
            mAnimationStartTime = now();
        }

        if (isAnimating()) {
            canvas.drawMixed(mTexture, PLACEHOLDER_COLOR, getRatio(), x, y,
                    width, height);
        } else {
            mTexture.draw(canvas, x, y, width, height);
        }
    }

    @Override
    public void draw(GLCanvas canvas, RectF source, RectF dest) {
        if (mBitmap == null) {
            canvas.fillRect(dest.left, dest.top, dest.width(), dest.height(),
                    PLACEHOLDER_COLOR);
            return;
        }

        if (mTexture == null) {
            mTexture = new BitmapTexture(mBitmap);
        }

        canvas.drawTexture(mTexture, source, dest);
    }

    public boolean isAnimating() {
        if (mAnimationStartTime < 0) return false;
        if (now() - mAnimationStartTime >= DURATION) {
            mAnimationStartTime = ANIMATION_DONE;
            return false;
        }
        return true;
    }

    private static long now() {
        return AnimationTime.get();
    }

    private float getRatio() {
        float r = (float)(now() - mAnimationStartTime) / DURATION;
        return Utils.clamp(1.0f - r, 0.0f, 1.0f);
    }

    public boolean isShowingPlaceholder() {
        return (mBitmap == null) || isAnimating();
    }
}