原理:
原图和倒影图分解成两个Bitmap, 倒影的Bitmap设计为原图的高度一半,宽度一致。然后创建一个可变空的Bitmap, 宽度跟原图保持一致,宽度为原图的1.5倍(宽度包括原图和倒影图的宽度之和),然后用Canvas关联这个可变空的Bitmap,在Canvas上将原 图和倒影图依次绘制上去就行,为了更接近倒影的效果,需要设计渐变等效果。
主要逻辑如下:
PorterDuffXfermode 定义的模式如下:
- import android.app.Activity;
- import android.graphics.Bitmap;
- import android.graphics.BitmapFactory;
- import android.graphics.Canvas;
- import android.graphics.LinearGradient;
- import android.graphics.Matrix;
- import android.graphics.Paint;
- import android.graphics.PorterDuff;
- import android.graphics.PorterDuffXfermode;
- import android.graphics.Shader;
- import android.graphics.drawable.BitmapDrawable;
- import android.os.Bundle;
- import android.widget.ImageView;
- public class MainActivity extends Activity {
- private ImageView mRevertImageView;
- private Bitmap mSourceBitmap; //原图
- private Bitmap mRevertBitmap; //倒立图
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- mRevertImageView = (ImageView)findViewById(R.id.im_revert);
- mSourceBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.source);
- mRevertImageView.setBackground(new BitmapDrawable(getResources(), revertBitmap()));
- }
- private Bitmap revertBitmap() {
- //1.倒立图
- Matrix matrix = new Matrix();
- matrix.preScale(1, -1); //以X轴向下翻转
- int width = mSourceBitmap.getWidth();
- int height = mSourceBitmap.getHeight();
- //生成倒立图,宽度和原图一致,高度为原图的一半
- mRevertBitmap = Bitmap.createBitmap(mSourceBitmap, 0, height / 2, width, height / 2, matrix, false);
- //2.要生成原图加上倒立图,先生成一个可变空的Bitmap, 高度为原图高度的1.5倍(包括原图和倒立图的高度)
- int gap = 10; //间隙空白
- Bitmap bitmap = Bitmap.createBitmap(width, height + height / 2, Bitmap.Config.ARGB_8888);
- Paint paint = new Paint();
- Canvas canvas = new Canvas(bitmap);
- canvas.drawBitmap(mSourceBitmap, 0, 0, paint); //绘制原图
- canvas.drawBitmap(mRevertBitmap, 0, height + gap, paint); //绘制倒立图
- //3.画笔使用LinearGradient 线性渐变渲染
- LinearGradient lg = new LinearGradient(0, height + gap, width, bitmap.getHeight(), 0xabff0000, 0x00ffff00, Shader.TileMode.MIRROR);
- paint.setShader(lg);
- //4.指定画笔的Xfermode 即绘制的模式(不同的模式,绘制的区域不同)
- paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));
- //5.在倒立图区,绘制矩形渲染图层
- canvas.drawRect(0, height + gap, width, bitmap.getHeight(), paint);
- paint.setXfermode(null);
- return bitmap;
- }
- //缩放图片
- private Bitmap resizeImage(Bitmap bitmap, int width, int height) {
- int originWidth = bitmap.getWidth();
- int originHeight = bitmap.getHeight();
- float scaleWidth = width / originWidth;
- float scaleHeight = height / originHeight;
- Matrix matrix = new Matrix();
- matrix.postScale(scaleWidth, scaleHeight);
- Bitmap resizeBitmap = Bitmap.createBitmap(bitmap, 0, 0, originWidth, originHeight, matrix, true);
- return resizeBitmap;
- }
- }
来源: http://www.phpxs.com/code/1001633/