在畫圖的時候,圖片如果旋轉或縮放之后,總是會出現那些華麗的鋸齒。其實Android自帶了解決方式。
方法一:給Paint加上抗鋸齒標志。然后將Paint對象作為參數傳給canvas的繪制方法。

Java代碼 復制代碼 收藏代碼
  1. paint.setAntiAlias( true );

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方法二:給Canvas加上抗鋸齒標志。
有些地方不能用paint的,就直接給canvas加抗鋸齒,更方便。

Java代碼 復制代碼 收藏代碼
  1. canvas.setDrawFilter( new PaintFlagsDrawFilter( 0 , Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG));

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測試代碼如下:

Java代碼 復制代碼 收藏代碼
  1. import android.content.Context;
  2. import android.graphics.Bitmap;
  3. import android.graphics.BitmapFactory;
  4. import android.graphics.Canvas;
  5. import android.graphics.Matrix;
  6. import android.graphics.Paint;
  7. import android.graphics.PaintFlagsDrawFilter;
  8. import android.view.View;
  9. public class MyView extends View {
  10. private PaintFlagsDrawFilter pfd;
  11. private Paint mPaint = new Paint();
  12. private Matrix matrix = new Matrix();;
  13. private Bitmap bmp;
  14. public MyView(Context context) {
  15. super (context);
  16. initialize();
  17. }
  18. private void initialize() {
  19. pfd = new PaintFlagsDrawFilter( 0 , Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);
  20. mPaint.setAntiAlias( true );
  21. matrix.setRotate( 30 );
  22. matrix.postScale( 0 .5f, 0 .5f);
  23. bmp = BitmapFactory.decodeResource(getResources(), R.drawable.show);
  24. }
  25. @Override
  26. public void dispatchDraw(Canvas canvas) {
  27. canvas.translate( 100 , 0 );
  28. canvas.drawBitmap(bmp, matrix, null );
  29. canvas.translate( 0 , 250 );
  30. canvas.drawBitmap(bmp, matrix, mPaint);
  31. canvas.setDrawFilter(pfd);
  32. canvas.translate( 0 , 250 );
  33. canvas.drawBitmap(bmp, matrix, null );
  34. }
  35. }

下圖是效果:

Android 畫圖之抗鋸齒

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