Android Learning notes Advanced 18 drawing and saving pictures to local

1, first create a bitmap picture, and specify the size;

2. Create a new canvas on the picture, then draw it on the canvas and save it;

3, need to save the directory file, note if the write directory such as "/sdcard/song/" if not exist, you must first create (File.mkdirs).

4, need to add permissions: <uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/>

Canvas is a canvas, you can create a blank canvas, just new one canvas object, no parameters required. You can also use Bitmapfactory to create a bitmap object, as a new canvas object parameter, that is, the canvas is not blank, if you want to save the picture, it is best to bitmap is a new, rather than from a file to read in, or a Drawable object. Then use Canvas to draw the first picture, on the second picture, and finally use Canvas.save (int flag) method to save, note that the Save method inside the parameters can save a single layer, if it is to save all layers, use Save (Canvas.all_ Save_flag).

If you do not understand the picture rotation problem, please see the blog: Android learning note Bitmap bitmap rotation
This is the original picture and the post-rotation picture

This is the image saved to the local 800*600 jpg format

Specific implementation:

[Java]View PlainCopy

2. Package xiaosi.bitmap;
6. Import android.app.Activity;
8. Import Android.os.Bundle;
12. Public class Mianactivity extends Activity
14. {
18. private Bitmapview Bitmapview = null;
20. @Override
22. protected void OnCreate (Bundle savedinstancestate)
24. {
26. super.oncreate (savedinstancestate);
28. Bitmapview = New Bitmapview (this);
30. Setcontentview (Bitmapview);
32. }
34. }

Bitmapview.java

[Java]View PlainCopy

2. Package xiaosi.bitmap;
6. Import Java.io.File;
8. Import Java.io.FileOutputStream;
12. Import Android.content.Context;
14. Import android.content.res.Resources;
16. Import Android.graphics.Bitmap;
18. Import Android.graphics.Bitmap.Config;
20. Import Android.graphics.BitmapFactory;
22. Import Android.graphics.Canvas;
24. Import Android.graphics.Color;
26. Import Android.graphics.Matrix;
28. Import Android.view.View;
32. Public class Bitmapview extends View
34. {
36. private Matrix Matrix = null;
38. Public Bitmapview (context context)
40. {
42. super (context);
44. }
48. public void OnDraw (canvas canvas)
50. {
54. //Get reference to resource file res
56. Resources res = getresources ();
58. //Get graphics resource files
60. Bitmap BMP = Bitmapfactory.decoderesource (res, r.drawable.h);
62. //Set canvas canvas background to white
64. Canvas.drawcolor (Color.Black);
66. Canvas.drawbitmap (BMP, 0, 0, null);
68. //define matrix object
70. Matrix = new Matrix ();
72. //Rotate 30 degrees
74. Matrix.postrotate (30);
76. Bitmap Bitmap = Bitmap.createbitmap (BMP, 0, bmp.getwidth (), bmp.getheight ()/2,
78. Matrix, true);
80. Canvas.drawbitmap (Bitmap, 0, + , null);
82. Savebitmap (bitmap);
84. }
86. //Save to local
88. public void Savebitmap (Bitmap bmp)
90. {
92. Bitmap Bitmap = Bitmap.createbitmap (+, config.argb_8888);
94. Canvas canvas = new canvas (bitmap);
96. //Load background image
98. Bitmap BMPs = Bitmapfactory.decoderesource (Getresources (), r.drawable.playerbackground);
100. Canvas.drawbitmap (BMPs, 0, 0, null);
102. //load the screen to be saved
104. Canvas.drawbitmap (BMP, ten, + , null);
106. //Save All Layers
108. Canvas.save (Canvas.all_save_flag);
110. Canvas.restore ();
112. //Storage path
114. File File = new file ("/sdcard/song/");
116. if (!file.exists ())
118. File.mkdirs ();
120. try {
122. FileOutputStream FileOutputStream = new FileOutputStream (File.getpath () + "/xuanzhuan.jpg");
124. Bitmap.compress (Bitmap.CompressFormat.JPEG, fileoutputstream);
126. Fileoutputstream.close ();
128. System.out.println ("savebmp is Here");
130. } catch (Exception e) {
132. E.printstacktrace ();
134. }
136. }
138. }

Source code Download: Click to open the link

Android Learning notes Advanced 18 drawing and saving pictures to local