Android hand-drawn-images can be saved

Draw a very ugly robot...

Add the key code:

MainView. java

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Package com. tszy. views;
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Import java. io. File;
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Import java. io. FileNotFoundException;
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Import java. io. FileOutputStream;
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Import java. io. IOException;
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Import android. content. Context;
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Import android. graphics. Bitmap;
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Import android. graphics. Bitmap. CompressFormat;
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Import android. graphics. Bitmap. Config;
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Import android. graphics. Canvas;
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Import android. graphics. Color;
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Import android. graphics. Paint;
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Import android. graphics. Path;
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Import android. util. AttributeSet;
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Import android. view. MotionEvent;
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Import android. view. View;
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Public class MainView extends View {
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Private Paint paint;
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Private Canvas cacheCanvas;
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Private Bitmap cachebBitmap;
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Private Path path;
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Private int clr_bg, clr_fg;
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Public MainView (Context context, AttributeSet attrs ){
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Super (context, attrs );
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Clr_bg = Color. WHITE;
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Clr_fg = Color. CYAN;
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Paint = new Paint ();
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Paint. setAntiAlias (true); // anti-aliasing
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Paint. setStrokeWidth (3); // line width
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Paint. setStyle (Paint. Style. STROKE); // draw the outline
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Paint. setColor (clr_fg); // color
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Path = new Path ();
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// Create a screen size bitmap as a buffer
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CachebBitmap = Bitmap. createBitmap (480,800, Config. ARGB_8888 );
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CacheCanvas = new Canvas (cachebBitmap );
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CacheCanvas. drawColor (clr_bg );
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}
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Public MainView (Context context ){
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Super (context );
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}
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@ Override
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Protected void onDraw (Canvas canvas ){
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Canvas. drawColor (clr_bg );
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// Draw the last image; otherwise, the image is inconsistent.
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Canvas. drawBitmap (cachebBitmap, 0, 0, null );
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Canvas. drawPath (path, paint );
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}
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/**
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* Clear the canvas
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*/
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Public void clear (){
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Path. reset ();
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CacheCanvas. drawColor (clr_bg );
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Invalidate ();
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}
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/**
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* Save the content of the canvas to a file.
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* @ Param filename
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* @ Throws FileNotFoundException
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*/
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Public void saveToFile (String filename) throws FileNotFoundException {
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File f = new File (filename );
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If (f. exists ())
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Throw new RuntimeException ("file:" + filename + "already exists! ");
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FileOutputStream fos = new FileOutputStream (new File (filename ));
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// Compress bitmap into image data of other formats
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CachebBitmap. compress (CompressFormat. PNG, 50, fos );
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Try {
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Fos. close ();
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} Catch (IOException e ){
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// TODO Auto-generated catch block
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E. printStackTrace ();
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}
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}
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Private float cur_x, cur_y;
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Private boolean isMoving;
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@ Override
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Public boolean onTouchEvent (MotionEvent event ){
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// TODO Auto-generated method stub
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Float x = event. getX ();
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Float y = event. getY ();
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Switch (event. getAction ()){
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Case MotionEvent. ACTION_DOWN :{
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Cur_x = x;
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Cur_y = y;
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Path. moveTo (cur_x, cur_y );
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IsMoving = true;
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Break;
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}
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Case MotionEvent. ACTION_MOVE :{
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If (! IsMoving)
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Break;
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// Draw the quadratic curve
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Path. quadTo (cur_x, cur_y, x, y );
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// The method below seems to be the same as above
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// Path. lineTo (x, y );
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Cur_x = x;
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Cur_y = y;
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Break;
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}
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Case MotionEvent. ACTION_UP :{
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// Hover the mouse to save the final state
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CacheCanvas. drawPath (path, paint );
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Path. reset ();
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IsMoving = false;
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Break;
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}
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}
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// Notification refresh Interface
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Invalidate ();
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Return true;
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}
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}
Activity Code:

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@ Override
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Public void onClick (View v ){
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// TODO Auto-generated method stub
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Switch (v. getId ()){
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Case R. id. iv_btn_clear:
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View. clear ();
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Break;
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Case R. id. iv_btn_save :{
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Try {
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String sdState = Environment. getExternalStorageState (); // determines whether the SD card exists.
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// Check whether the SD card is available
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If (! SdState. equals (android. OS. Environment. MEDIA_MOUNTED )){
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Toast. makeText (this, "the SD card is not ready! ", Toast. LENGTH_SHORT). show ();
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Break;
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}
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// Obtain the system image storage path
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File path = Environment. getExternalStoragePublicDirectory (Environment. DIRECTORY_PICTURES );
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// Make sure the Pictures directory exists.
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Path. mkdirs ();
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// Generate an image name based on the current time
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Calendar c = Calendar. getInstance ();
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String name = ""
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+ C. get (Calendar. YEAR) + c. get (Calendar. MONTH) + c. get (Calendar. DAY_OF_MONTH)
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+ C. get (Calendar. HOUR_OF_DAY) + c. get (Calendar. MINUTE) + c. get (Calendar. SECOND)
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+ ". Png ";
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// Synthesize the complete path, note/delimiter
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String string = path. getPath () + "/" + name;
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View. saveToFile (string );
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Toast. makeText (this, "saved successfully! \ N files are saved in: "+ string, Toast. LENGTH_LONG). show ();
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} Catch (FileNotFoundException e ){
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Toast. makeText (this, "failed to save! \ N "+ e, Toast. LENGTH_LONG). show ();
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}
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Break;
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}
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}
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}
There is no difficulty. It mainly refers to converting Bitmap to a PNG image. After looking for a while, I found that the Canvas is not directly or indirectly saved. I used double buffering here, the content bitmap of another canvas is created by yourself. Naturally, you can save the bitmap of this canvas as a file.

Check that Bitmap has a compress (CompressFormat format, int quality, OutputStream stream) method. It is obvious that it is OK to pass the file output to this method.