Android开发：轻松实现图片倒影效果

2021-07-25 20:54:50

效果如下：

<ignore_js_op> Android开发：轻松实现图片倒影效果

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2011-12-11 09:46 上传

主要代码如下：

public static Bitmap createReflectedImage(Bitmap originalImage) {
final int reflectionGap = 4;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
height / 2, width, height / 2, matrix, false);
Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
(height + height / 2), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(originalImage, 0, 0, null);
Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0×70ffffff, 0×00ffffff,
TileMode.MIRROR);
paint.setShader(shader);
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
return bitmapWithReflection;
}

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解释一下：

Matrix matrix = new Matrix();
matrix.preScale(1, -1);

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实现图片的反转，见Android利用Matrix简单处理图片。

Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
height / 2, width, height / 2, matrix, false);

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创建反转后的图片Bitmap对象，图片高是原图的一半。

Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
(height + height / 2), Config.ARGB_8888);

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创建标准的Bitmap对象，宽和原图一致，高是原图的1.5倍。

Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(originalImage, 0, 0, null);

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创建画布对象，将原图画于画布，起点是原点位置。

Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);

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将反转后的图片画到画布中。

LinearGradient shader = new LinearGradient(0,
originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0×70ffffff, 0×00ffffff,

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创建线性渐变LinearGradient 对象。

canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);

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画布画出反转图片大小区域，然后把渐变效果加到其中，就出现了图片的倒影效果。

Android开发：轻松实现图片倒影效果