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  • Android放大镜的实现

    package chroya.demo.magnifier;


    import android.content.Context;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.BitmapShader;
    import android.graphics.Canvas;
    import android.graphics.Matrix;
    import android.graphics.Shader.TileMode;
    import android.graphics.drawable.ShapeDrawable;
    import android.graphics.drawable.shapes.OvalShape;
    import android.view.MotionEvent;
    import android.view.View;


    /**
     * 放大镜实现方式1
     * @author chroya
     *
     */
    public class ShaderView extends View{
    private Bitmap bitmap;
    private ShapeDrawable drawable;
    //放大镜的半径
    private static final int RADIUS = 80;
    //放大倍数
    private static final int FACTOR = 3;
    private Matrix matrix = new Matrix();


    public ShaderView(Context context) {
    super(context);
    Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.show);
    bitmap = bmp;
    BitmapShader shader = new BitmapShader(
    Bitmap.createScaledBitmap(bmp, bmp.getWidth()*FACTOR,
    bmp.getHeight()*FACTOR, true), TileMode.CLAMP, TileMode.CLAMP);
    //圆形的drawable
    drawable = new ShapeDrawable(new OvalShape());
    drawable.getPaint().setShader(shader);
    drawable.setBounds(0, 0, RADIUS*2, RADIUS*2);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
    final int x = (int) event.getX();
    final int y = (int) event.getY();
    //这个位置表示的是,画shader的起始位置
    matrix.setTranslate(RADIUS-x*FACTOR, RADIUS-y*FACTOR);
    drawable.getPaint().getShader().setLocalMatrix(matrix);
    //bounds,就是那个圆的外切矩形
    drawable.setBounds(x-RADIUS, y-RADIUS, x+RADIUS, y+RADIUS);
    invalidate();
    return true;
    }

    @Override
    public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawBitmap(bitmap, 0, 0, null);
    drawable.draw(canvas);
    }

    }


    二:

    package chroya.demo.magnifier;


    import android.content.Context;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.Canvas;
    import android.graphics.Matrix;
    import android.graphics.Path;
    import android.graphics.Path.Direction;
    import android.view.MotionEvent;
    import android.view.View;


    /**
     * 放大镜实现方式2
     * @author chroya
     *
     */
    public class PathView extends View{
    private Path mPath = new Path();
    private Matrix matrix = new Matrix();
    private Bitmap bitmap;
    //放大镜的半径
    private static final int RADIUS = 80;
    //放大倍数
    private static final int FACTOR = 2;
    private int mCurrentX, mCurrentY;


    public PathView(Context context) {
    super(context);
    mPath.addCircle(RADIUS, RADIUS, RADIUS, Direction.CW);
    matrix.setScale(FACTOR, FACTOR);

    bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.show);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
    mCurrentX = (int) event.getX();
    mCurrentY = (int) event.getY();

    invalidate();
    return true;
    }

    @Override
    public void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //底图
    canvas.drawBitmap(bitmap, 0, 0, null);
    //剪切
    canvas.translate(mCurrentX - RADIUS, mCurrentY - RADIUS);
    canvas.clipPath(mPath);
    //画放大后的图
    canvas.translate(RADIUS-mCurrentX*FACTOR, RADIUS-mCurrentY*FACTOR);
    canvas.drawBitmap(bitmap, matrix, null);
    }
    }

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  • 原文地址:https://www.cnblogs.com/aukle/p/3233726.html
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