一、相关概念
1、Drawable就是一个可画的对象，其可能是一张位图（BitmapDrawable），也可能是一个图形（ShapeDrawable），还有可能是一个图层（LayerDrawable），我们根据画图的需求，创建相应的可画对象
2、Canvas画布，绘图的目的区域，用于绘图
3、Bitmap位图，用于图的处理
4、Matrix矩阵
二、Bitmap
1、从资源中获取Bitmap
Resources res = getResources();
Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.icon);
2、Bitmap → byte[]
[] Bitmap2Bytes(Bitmap bm) {
ByteArrayOutputStream baos = ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
baos.toByteArray();
}
3、byte[] → Bitmap
Bitmap Bytes2Bimap([] b) {
(b.length != 0) {
BitmapFactory.decodeByteArray(b, 0, b.length);
} {
;
}
}
4、Bitmap缩放
Bitmap zoomBitmap(Bitmap bitmap, width, height) {
w = bitmap.getWidth();
h = bitmap.getHeight();
Matrix matrix = Matrix();
scaleWidth = (() width / w);
scaleHeight = (() height / h);
matrix.postScale(scaleWidth, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, );
newbmp;
}
5、将Drawable转化为Bitmap
Bitmap drawableToBitmap(Drawable drawable) {
w = drawable.getIntrinsicWidth();
h = drawable.getIntrinsicHeight();
Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565;
Bitmap bitmap = Bitmap.createBitmap(w, h, config);
Canvas canvas = Canvas(bitmap);
drawable.setBounds(0, 0, w, h);
drawable.draw(canvas);
bitmap;
}
6、获得圆角图片
Bitmap getRoundedCornerBitmap(Bitmap bitmap, roundPx) {
w = bitmap.getWidth();
h = bitmap.getHeight();
Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);
Canvas canvas = Canvas(output);
color = 0xff424242;
Paint paint = Paint();
Rect rect = Rect(0, 0, w, h);
RectF rectF = RectF(rect);
paint.setAntiAlias();
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode( PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
output;
}
7、获得带倒影的图片
Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {
reflectionGap = 4;
w = bitmap.getWidth();
h = bitmap.getHeight();
Matrix matrix = Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,
h / 2, matrix, );
Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),
Config.ARGB_8888);
Canvas canvas = Canvas(bitmapWithReflection);
canvas.drawBitmap(bitmap, 0, 0, );
Paint deafalutPaint = Paint();
canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint);
canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, );
Paint paint = Paint();
LinearGradient shader = LinearGradient(0, bitmap.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,
0x00ffffff, TileMode.CLAMP);
paint.setShader(shader);
paint.setXfermode( PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
bitmapWithReflection;
}
三、Drawable
1、Bitmap转换成Drawable
Bitmap bm=xxx; BitmapDrawable bd= BitmapDrawable(getResource(), bm);
因为BtimapDrawable是Drawable的子类，最终直接使用bd对象即可。
2、Drawable缩放
Drawable zoomDrawable(Drawable drawable, w, h) {
width = drawable.getIntrinsicWidth();
height = drawable.getIntrinsicHeight();
Bitmap oldbmp = drawableToBitmap(drawable);
Matrix matrix = Matrix();
sx = (() w / width);
sy = (() h / height);
matrix.postScale(sx, sy);
Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
matrix, );
BitmapDrawable(newbmp);
}
