Question

请帮助我找到promblem或编辑我的代码，将画布保存到png flie。

（嗯，我可以保存但不能打开它，我的png是黑色的。）

对不起我的工作。

CanvasView.class

 public Bitmap saveSignature() {

    Bitmap bitmap = Bitmap.createBitmap(this.getWidth(), this.getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    this.draw(canvas);
    Calendar calendar=Calendar.getInstance();
    //File file = new File(Environment.getExternalStorageDirectory() + "/Pictures/sign"+calendar.getTimeInMillis()+".png");
    File file = Environment.getExternalStorageDirectory();
    File newFile = new File(file, "test"+calendar.getTimeInMillis()+".png");

    try {
        //bitmap.compress(Bitmap.CompressFormat.PNG, 100, new FileOutputStream(file));
        FileOutputStream fileOutputStream = new FileOutputStream(newFile);
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
        fileOutputStream.flush();
        fileOutputStream.close();


        Log.e("file", file.getAbsolutePath());
    } catch (Exception e) {
        e.printStackTrace();
        Log.e("Exception", e.getLocalizedMessage());
    }
    return bitmap;
}

Main.class

     public void saveCanvas(View view) {
    if (ActivityCompat.checkSelfPermission(this, permissions[0]) == 1) {

        ivSignature.setImageBitmap(canvasView.saveSignature());
        canvasView.clearCanvas();

    } else {
        ActivityCompat.requestPermissions(this, permissions, REQUEST_CODE);
    }

}

Answer 1

PNG是黑色的，因为它是透明的。初始化时将其着色。您可以使用以下代码段将当前画布保存为.png图像。它安静简单。

customCanvas.setDrawingCacheEnabled(true);
String imgSaved = MediaStore.Images.Media.insertImage(getActivity().getContentResolver(), customCanvas.getDrawingCache(),UUID.randomUUID().toString()+".png", "drawing");
if(imgSaved!=null){

    //do something here

    }
    else{

   //do something here

}

Answer 2

参考以下代码段

将画布保存到图像

RelativeLayout z = (RelativeLayout) findViewById(R.id.CardMakerrl);
z.setDrawingCacheEnabled(true);
z.buildDrawingCache();
Bitmap bitmapSetDrawingChache = Bitmap.createBitmap(z.getDrawingCache());
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try {
    bitmapSetDrawingChache.compress(Bitmap.CompressFormat.PNG, 100, byteArrayOutputStream);
}catch (Exception e)
{
    Toast.makeText(CardMaker.this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
// saving in sdcard
File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "My Folder" + File.separator);
if(!file.exists())
    file.mkdirs();

String imageName = "Data-" + DateFormat.getDateTimeInstance().format(new Date()) + ".jpg";
final File fileImagePath = new File(file.getAbsolutePath(), imageName);
FileOutputStream fileOutputStream = new FileOutputStream(fileImagePath);
fileOutputStream.write(byteArrayOutputStream.toByteArray());
fileOutputStream.close();

Android - Canvas保存图片（关闭）

2 个答案: