Android画布的保存,androidcanvas绘制bitmap并保存到本地

自定义一个view&＃xff0c;重载draw方法(不是重载ondraw&＃xff0c;不然图片保存下来是空白的。)

自定义一个view&＃xff0c;重载draw方法(不是重载ondraw&＃xff0c;不然图片保存下来是空白的。)在activity里面findviewbyid找到view&＃xff0c;用view调用draw方法。

在activity的oncreate里面&＃xff1a;

if (mBackgroundBitmap &＃61;&＃61; null) {

mBackgroundBitmap &＃61; Bitmap.createBitmap(screenWidth, screenHeight, Bitmap.Config.RGB_565);

canvas &＃61; new Canvas(mBackgroundBitmap);

}

myView.draw(canvas);

自定义的myView(extend View)里面&＃xff0c;

&＃64;Override

public void draw(Canvas canvas) {

//canvas.drawLine().....

}

保存到本地&＃xff1a;

activity里面一些方法&＃xff0c;

public Bitmap getBitmap() {

Bitmap whiteBgBitmap &＃61; Bitmap.createBitmap(mBackgroundBitmap.getWidth(), mBackgroundBitmap.getHeight(),

Bitmap.Config.ARGB_8888);

Canvas canvas &＃61; new Canvas(whiteBgBitmap);

canvas.drawColor(Color.WHITE);

canvas.drawBitmap(mBackgroundBitmap, 0, 0, null);

return whiteBgBitmap;

}public boolean addGraphToGallery(Bitmap bmp) {

boolean result &＃61; false;

try {

File photo &＃61; new File(getAlbumStorageDir("cece"), String.format("cece_bitmap_%d.jpg",

System.currentTimeMillis()));

saveBitmapToJPG(bmp, photo);

Intent mediaScanIntent &＃61; new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);

Uri contentUri &＃61; Uri.fromFile(photo);

mediaScanIntent.setData(contentUri);

SpiderNetActivity.this.sendBroadcast(mediaScanIntent);

result &＃61; true;

} catch (IOException e) {

e.printStackTrace();

}

return result;

}public void saveBitmapToJPG(Bitmap bitmap, File photo) throws IOException {

Bitmap newBitmap &＃61; Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);

Canvas canvas &＃61; new Canvas(newBitmap);

canvas.drawColor(Color.WHITE);

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

OutputStream stream &＃61; new FileOutputStream(photo);

newBitmap.compress(Bitmap.CompressFormat.JPEG, 80, stream);

stream.close();

}public File getAlbumStorageDir(String albumName) {

// Get the directory for the user&＃39;s public pictures directory.

File file &＃61; new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), albumName);

if (!file.mkdirs()) {

Log.e("SignaturePad", "Directory not created");

}

return file;

}开始保存&＃xff1a;

Bitmap spiderNetBitmap &＃61; getBitmap();

if (addGraphToGallery(spiderNetBitmap)) {

Toast.makeText(SpiderNetActivity.this, "Spider graph saved into the Gallery", Toast.LENGTH_SHORT)

.show();

} else {

Toast.makeText(SpiderNetActivity.this, "Unable to store Spider graph", Toast.LENGTH_SHORT).show();

}不要忘记在manifest里面添加存储权限&＃xff1a;

bitmap转byte[] 方法&＃xff1a;

public byte[] Bitmap2Bytes(Bitmap bm) {

ByteArrayOutputStream baos &＃61; new ByteArrayOutputStream();

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

return baos.toByteArray();

}

&＃xff0c;