自定义ImageView实现自动放大缩小动画

来源：互联网发布：java 服务器文件同步编辑：程序博客网时间：2024/05/22 11:44

许久不见的第二篇博客

这篇讲的是如何生成一个自定义的ImageView，实现自动放大缩小动画。
为什么实现这个功能呢？因为我想在ViewPager实现图片放大缩小的动画，但是ViewPager几个页面的动画会一起动，而且放大全屏图片的话会相互覆盖，很诡异。于是上网搜demo，一无所获。迫于无奈。。。
废话不多说，直接贴代码。

1.配置文件直接添加

当直接在布局文件中添加图片的话，可以在自定义View代码中用getDrawable（）获取图片资源，然后通过DrawBitmap绘制图片。通过不断绘制图片的位置，达到放大缩小的功能。
第一种情况实在XML布局文件中直接添加的：

public class CoolImageView extends ImageView {    private int mLeft = 0;    private int mTop = 0;    private Handler mHandler;    private Bitmap bitmap;    private Rect srcRect = new Rect();    private Rect dstRect = new Rect();    private int imgWidth;    private int imgHeight;    private boolean flag;    private boolean istart;    public CoolImageView(Context context) {        super(context);    }    public CoolImageView(Context context, AttributeSet attrs) {        super(context, attrs);        setUp(context, attrs);    }    public CoolImageView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        setUp(context, attrs);    }    private void setUp(Context context, AttributeSet attrs) {        mHandler = new MoveHandler();        mHandler.sendEmptyMessageDelayed(1, 220L);        istart = true;    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        int width = getWidth();        int height = getHeight();        //获取图片资源        BitmapDrawable drawable = (BitmapDrawable) getDrawable();        bitmap = drawable.getBitmap();        dstRect.left = 0;        dstRect.top = 0;        dstRect.right = width;        dstRect.bottom = height;        if (bitmap != null) {            if (istart) {//                获取图片的宽高                imgWidth = bitmap.getWidth();                imgHeight = bitmap.getHeight();                srcRect.left = 0 + mLeft;                srcRect.right = imgWidth - mLeft;                srcRect.top = 0 + mTop;                srcRect.bottom = imgHeight - mTop;                canvas.drawBitmap(bitmap, srcRect, dstRect, null);            } else {                canvas.drawBitmap(bitmap, null, dstRect, null);            }        }    }    private class MoveHandler extends Handler {        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case 1:                    if (imgHeight != 0) {                        if (mTop == 0) {                            mTop += 5;                            mLeft += 5;                        } else if (mTop == 120) {                            mTop -= 5;                            mLeft -= 5;                        }                    }                    postInvalidate();                    mHandler.sendEmptyMessageDelayed(1, 250);                    break;            }        }    }    public void start() {        mTop = 0;        mLeft = 0;        istart = true;        mHandler.sendEmptyMessageDelayed(1, 220L);    }    public void stop() {        istart = false;    }}

2 .通过Glide加载图片的方式

通过Glide加载图片的话，不能直接用getDrawable获取图片资源。Glide加载图片的方式也需要改变。废话不多说，直接上代码。
CoolimageView直接从Glide的缓存中加载图片。

Glide.with(GoodsPagerActivity.this)                        .load(sList.get(position).img)                        .override(width, height)                        .centerCrop()                        .into(new SimpleTarget<GlideDrawable>() {                            @Override                            public void onResourceReady(GlideDrawable resource, GlideAnimation<? super GlideDrawable> glideAnimation) {                                imageView.setImageDrawable(resource);                            }                        });CoolImageView.java:唯一不同的是获取图片的方式；```javapublic class CoolImageView extends ImageView {    private int mLeft = 0;    private int mTop = 0;    private Handler mHandler;    private Bitmap bitmap;    private Rect srcRect = new Rect();    private Rect dstRect = new Rect();    private int imgWidth;    private int imgHeight;    private boolean flag;    private boolean istart;    private int width;    private int height;    public CoolImageView(Context context) {        super(context);    }    public CoolImageView(Context context, AttributeSet attrs) {        super(context, attrs);        setUp(context, attrs);    }    public CoolImageView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        setUp(context, attrs);    }    private void setUp(Context context, AttributeSet attrs) {        mHandler = new MoveHandler();        mHandler.sendEmptyMessageDelayed(1, 220L);        istart = true;    }    @Override    public void setImageDrawable(@Nullable Drawable drawable) {        super.setImageDrawable(drawable);        if (mHandler != null) {            mHandler.sendEmptyMessageDelayed(1, 220L);        } else {            mHandler = new MoveHandler();            mHandler.sendEmptyMessageDelayed(1, 220L);            istart = true;        }    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        width = getWidth();        height = getHeight();        GlideBitmapDrawable drawable = (GlideBitmapDrawable) getDrawable();        if (drawable != null) {            bitmap = drawable.getBitmap();        }        dstRect.left = 0;        dstRect.top = 0;        dstRect.right = width;        dstRect.bottom = height;        if (bitmap != null) {            if (istart) {                imgWidth = bitmap.getWidth();                imgHeight = bitmap.getHeight();                srcRect.left = 0 + mLeft;                srcRect.right = imgWidth - mLeft;                srcRect.top = 0 + mTop;                srcRect.bottom = imgHeight - mTop;                canvas.drawBitmap(bitmap, srcRect, dstRect, null);            } else {                canvas.drawBitmap(bitmap, null, dstRect, null);            }        }    }    private class MoveHandler extends Handler {        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case 1:                    if (imgHeight != 0) {                        if (mTop == 0) {                            flag = true;                        } else if (mTop == 60) {                            flag = false;                        }                        if (!flag) {                            mTop -= 2;                            mLeft -= 1;                        } else {                            mTop += 2;                            mLeft += 1;                        }                    }                    postInvalidate();                    mHandler.sendEmptyMessageDelayed(1, 200);                    break;            }        }    }    public void start() {        mTop = 0;        mLeft = 0;        istart = true;        mHandler.sendEmptyMessageDelayed(1, 220L);    }    public void stop() {        istart = false;    }}

如果感觉动画不够流畅可以缩小线程等待时间

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