Android中Bitmap和Drawable           

Android 

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

Java代码  

1. Resources res = getResources();

2. Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.icon);

   Resources res = getResources(); Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.icon);

2、Bitmap → byte[]

Java代码  

1. public byte[] Bitmap2Bytes(Bitmap bm) {

2. ByteArrayOutputStream baos = new ByteArrayOutputStream();

3. bm.compress(Bitmap.CompressFormat.PNG, 100, baos);

4. return baos.toByteArray();

5. }

   public byte[] Bitmap2Bytes(Bitmap bm) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); return baos.toByteArray(); }

3、byte[] → Bitmap

Java代码  

1. public Bitmap Bytes2Bimap(byte[] b) {

2. if (b.length != 0) {

3. return BitmapFactory.decodeByteArray(b, 0, b.length);

4. } else {

5. return null;

6. }

7. }

   public Bitmap Bytes2Bimap(byte[] b) { if (b.length != 0) { return BitmapFactory.decodeByteArray(b, 0, b.length); } else { return null; } }

4、Bitmap缩放

Java代码  

1. public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {
2. int w = bitmap.getWidth();
3. int h = bitmap.getHeight();
4. Matrix matrix = new Matrix();
5. float scaleWidth = ((float) width / w);
6. float scaleHeight = ((float) height / h);
7. matrix.postScale(scaleWidth, scaleHeight);
8. Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
9. return newbmp;
10. }

public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        Matrix matrix = new Matrix();
        float scaleWidth = ((float) width / w);
        float scaleHeight = ((float) height / h);
        matrix.postScale(scaleWidth, scaleHeight);
        Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
        return newbmp;
    }

5、将Drawable转化为Bitmap

Java代码  

1. public static Bitmap drawableToBitmap(Drawable drawable) {

2. // 取 drawable 的长宽

3. int w = drawable.getIntrinsicWidth();

4. int h = drawable.getIntrinsicHeight();

5. // 取 drawable 的颜色格式

6. Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888

7. : Bitmap.Config.RGB_565;

8. // 建立对应 bitmap

9. Bitmap bitmap = Bitmap.createBitmap(w, h, config);

10. // 建立对应 bitmap 的画布

11. Canvas canvas = new Canvas(bitmap);

12. drawable.setBounds(0, 0, w, h);

13. // 把 drawable 内容画到画布中

14. drawable.draw(canvas);

15. return bitmap;

16. }

public static Bitmap drawableToBitmap(Drawable drawable) {
        // 取 drawable 的长宽
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();

        // 取 drawable 的颜色格式
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                : Bitmap.Config.RGB_565;
        // 建立对应 bitmap
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        // 建立对应 bitmap 的画布
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        // 把 drawable 内容画到画布中
        drawable.draw(canvas);
        return bitmap;
    }

6、获得圆角图片

Java代码  

1. public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {

2. int w = bitmap.getWidth();

3. int h = bitmap.getHeight();

4. Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);

5. Canvas canvas = new Canvas(output);

6. final int color = 0xff424242;

7. final Paint paint = new Paint();

8. final Rect rect = new Rect(0, 0, w, h);

9. final RectF rectF = new RectF(rect);

10. paint.setAntiAlias(true);

11. canvas.drawARGB(0, 0, 0, 0);

12. paint.setColor(color);

13. canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

14. paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));

15. canvas.drawBitmap(bitmap, rect, rect, paint);

16. return output;

17. }

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, w, h);
        final RectF rectF = new RectF(rect);
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);

        return output;
    }

7、获得带倒影的图片

Java代码  

1. public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {

2. final int reflectionGap = 4;

3. int w = bitmap.getWidth();

4. int h = bitmap.getHeight();

5. Matrix matrix = new Matrix();

6. matrix.preScale(1, -1);

7. Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,

8. h / 2, matrix, false);

9. Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),

10. Config.ARGB_8888);

11. Canvas canvas = new Canvas(bitmapWithReflection);

12. canvas.drawBitmap(bitmap, 0, 0, null);

13. Paint deafalutPaint = new Paint();

14. canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint);

15. canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, null);

16. Paint paint = new Paint();

17. LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0,

18. bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,

19. 0x00ffffff, TileMode.CLAMP);

20. paint.setShader(shader);

21. // Set the Transfer mode to be porter duff and destination in

22. paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));

23. // Draw a rectangle using the paint with our linear gradient

24. canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()

25. + reflectionGap, paint);

26. return bitmapWithReflection;

27. }

public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {
        final int reflectionGap = 4;
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();

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

        Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,
                h / 2, matrix, false);

        Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),
                Config.ARGB_8888);

        Canvas canvas = new Canvas(bitmapWithReflection);
        canvas.drawBitmap(bitmap, 0, 0, null);
        Paint deafalutPaint = new Paint();
        canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint);

        canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, null);

        Paint paint = new Paint();
        LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0,
                bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff,
                0x00ffffff, TileMode.CLAMP);
        paint.setShader(shader);
        // Set the Transfer mode to be porter duff and destination in
        paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
        // Draw a rectangle using the paint with our linear gradient
        canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()
                + reflectionGap, paint);

        return bitmapWithReflection;
    }

三、Drawable

1、Bitmap转换成Drawable

Java代码  

1. Bitmap bm=xxx; //xxx根据你的情况获取

2. BitmapDrawable bd= new BitmapDrawable(getResource(), bm);

3. 因为BtimapDrawable是Drawable的子类，最终直接使用bd对象即可。

   Bitmap bm=xxx; //xxx根据你的情况获取 BitmapDrawable bd= new 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

Java代码  

1. public static Drawable zoomDrawable(Drawable drawable, int w, int h) {
2. int width = drawable.getIntrinsicWidth();
3. int height = drawable.getIntrinsicHeight();
4. // drawable转换成bitmap
5. Bitmap oldbmp = drawableToBitmap(drawable);
6. // 创建操作图片用的Matrix对象
7. Matrix matrix = new Matrix();
8. // 计算缩放比例
9. float sx = ((float) w / width);
10. float sy = ((float) h / height);
11. // 设置缩放比例
12. matrix.postScale(sx, sy);
13. // 建立新的bitmap，其内容是对原bitmap的缩放后的图
14. Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
15. matrix, true);
16. return new BitmapDrawable(newbmp);
17. }