Android [advanced tutorial] the Android program calls local images and draws them.

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First, let's take a look at the layout. There is only one button and one image.

[Html] <? Xml version = "1.0" encoding = "UTF-8"?>
<LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"
Android: layout_width = "match_parent"
Android: layout_height = "match_parent"
Android: orientation = "vertical">
 
<Button
Android: id = "@ + id/button1"
Android: layout_width = "match_parent"
Android: layout_height = "wrap_content"
Android: text = "select image"/>
 
 
<ImageView
Android: id = "@ + id/imageView1"
Android: layout_width = "wrap_content"
Android: layout_height = "wrap_content"
Android: layout_gravity = "center_horizontal"
Android: src = "@ drawable/ic_launcher"/>
 
 
</LinearLayout>
<? Xml version = "1.0" encoding = "UTF-8"?>
<LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"
Android: layout_width = "match_parent"
Android: layout_height = "match_parent"
Android: orientation = "vertical">

<Button
Android: id = "@ + id/button1"
Android: layout_width = "match_parent"
Android: layout_height = "wrap_content"
Android: text = "select image"/>

<ImageView
Android: id = "@ + id/imageView1"
Android: layout_width = "wrap_content"
Android: layout_height = "wrap_content"
Android: layout_gravity = "center_horizontal"
Android: src = "@ drawable/ic_launcher"/>

</LinearLayout>
Next, click the button to call the local image program [java] // call the local image program
Intent choosePictureIntent = new Intent (Intent. ACTION_PICK,
Android. provider. MediaStore. Images. Media. EXTERNAL_CONTENT_URI );
StartActivityForResult (choosePictureIntent, 0 );
// Call the local image program
Intent choosePictureIntent = new Intent (Intent. ACTION_PICK,
Android. provider. MediaStore. Images. Media. EXTERNAL_CONTENT_URI );
StartActivityForResult (choosePictureIntent, 0 );
The next step is to process the selected image.

[Java] @ Override
Protected void onActivityResult (int requestCode, int resultCode, Intent data ){
// TODO Auto-generated method stub
Super. onActivityResult (requestCode, resultCode, data );
 
If (resultCode = RESULT_ OK ){
 
// Retrieve the Uri of the returned data
Uri imageFileUri = data. getData ();
// Obtain the current display area
Display currentDisplay = getWindowManager (). getdefadisplay Display ();
 
Float dw = currentDisplay. getWidth ();
Float dh = currentDisplay. getHeight ();
 
Try {
 
// Scale the image
BitmapFactory. Options BMP factoryoptions = new BitmapFactory. Options ();
BMP factoryoptions. inJustDecodeBounds = true;
Bmp = BitmapFactory
. DecodeStream (
GetContentResolver (). openInputStream (
ImageFileUri), null, BMP factoryoptions );
 
Int heightRatio = (int) Math. ceil (BMP factoryoptions. outHeight
/(Float) dh );
Int widthRatio = (int) Math. ceil (BMP factoryoptions. outWidth
/(Float) dw );
 
If (heightRatio> 1 & widthRatio> 1 ){
 
If (heightRatio> widthRatio ){
 
BMP factoryoptions. inSampleSize = heightRatio;
} Else {
BMP factoryoptions. inSampleSize = widthRatio;
}
 
}
 
BMP factoryoptions. inJustDecodeBounds = false;
// Scaled Image
Bmp = BitmapFactory
. DecodeStream (
GetContentResolver (). openInputStream (
ImageFileUri), null, BMP factoryoptions );
 
// Create a new image
AlteredBitmap = Bitmap. createBitmap (bmp. getWidth (),
Bmp. getHeight (), bmp. getConfig ());
 
Canvas = new Canvas (alteredBitmap );
Paint = new Paint ();
Paint. setColor (Color. GREEN );
// Adjust the paint width
Paint. setStrokeWidth (5 );
Matrix = new Matrix ();
Canvas. drawBitmap (bmp, matrix, paint );
 
ChoosenImageView. setImageBitmap (alteredBitmap );
ChoosenImageView. setOnTouchListener (this );
 
} Catch (Exception e ){
 
}
 
}
 
}
@ Override
Protected void onActivityResult (int requestCode, int resultCode, Intent data ){
// TODO Auto-generated method stub
Super. onActivityResult (requestCode, resultCode, data );

If (resultCode = RESULT_ OK ){

// Retrieve the Uri of the returned data
Uri imageFileUri = data. getData ();
// Obtain the current display area
Display currentDisplay = getWindowManager (). getdefadisplay Display ();

Float dw = currentDisplay. getWidth ();
Float dh = currentDisplay. getHeight ();

Try {

// Scale the image
BitmapFactory. Options BMP factoryoptions = new BitmapFactory. Options ();
BMP factoryoptions. inJustDecodeBounds = true;
Bmp = BitmapFactory
. DecodeStream (
GetContentResolver (). openInputStream (
ImageFileUri), null, BMP factoryoptions );

Int heightRatio = (int) Math. ceil (BMP factoryoptions. outHeight
/(Float) dh );
Int widthRatio = (int) Math. ceil (BMP factoryoptions. outWidth
/(Float) dw );

If (heightRatio> 1 & widthRatio> 1 ){

If (heightRatio> widthRatio ){

BMP factoryoptions. inSampleSize = heightRatio;
} Else {
BMP factoryoptions. inSampleSize = widthRatio;
}

}

BMP factoryoptions. inJustDecodeBounds = false;
// Scaled Image
Bmp = BitmapFactory
. DecodeStream (
GetContentResolver (). openInputStream (
ImageFileUri), null, BMP factoryoptions );

// Create a new image
AlteredBitmap = Bitmap. createBitmap (bmp. getWidth (),
Bmp. getHeight (), bmp. getConfig ());

Canvas = new Canvas (alteredBitmap );
Paint = new Paint ();
Paint. setColor (Color. GREEN );
// Adjust the paint width
Paint. setStrokeWidth (5 );
Matrix = new Matrix ();
Canvas. drawBitmap (bmp, matrix, paint );

ChoosenImageView. setImageBitmap (alteredBitmap );
ChoosenImageView. setOnTouchListener (this );

} Catch (Exception e ){

}

}

} Finally, the touch screen event.

[Java] float downx = 0;
Float downy = 0;
Float upx = 0;
Float upy = 0;
 
// Touch screen events
@ Override
Public boolean onTouch (View v, MotionEvent event ){
 
Int action = event. getAction ();
 
Switch (action ){
Case MotionEvent. ACTION_DOWN:
 
Downx = event. getX ();
Downy = event. getY ();
 
Break;
 
Case MotionEvent. ACTION_MOVE:
 
Upx = event. getX ();
Upy = event. getY ();
 
// Draw lines
Canvas. drawLine (downx, downy, upx, upy, paint );
// Refresh the ImageView
ChoosenImageView. invalidate ();
 
Downx = upx;
Downy = upy;
 
Break;
 
Case MotionEvent. ACTION_UP:
 
Upx = event. getX ();
Upy = event. getY ();
 
Canvas. drawLine (downx, downy, upx, upy, paint );
ChoosenImageView. invalidate ();
 
Break;
 
Case MotionEvent. ACTION_CANCEL:
 
Break;
 
Default:
Break;
}
 
Return true;
}
Float downx = 0;
Float downy = 0;
Float upx = 0;
Float upy = 0;

// Touch screen events
@ Override
Public boolean onTouch (View v, MotionEvent event ){

Int action = event. getAction ();

Switch (action ){
Case MotionEvent. ACTION_DOWN:

Downx = event. getX ();
Downy = event. getY ();

Break;

Case MotionEvent. ACTION_MOVE:

Upx = event. getX ();
Upy = event. getY ();

// Draw lines
Canvas. drawLine (downx, downy, upx, upy, paint );
// Refresh the ImageView
ChoosenImageView. invalidate ();

Downx = upx;
Downy = upy;

Break;

Case MotionEvent. ACTION_UP:

Upx = event. getX ();
Upy = event. getY ();

Canvas. drawLine (downx, downy, upx, upy, paint );
ChoosenImageView. invalidate ();

Break;

Case MotionEvent. ACTION_CANCEL:

Break;

Default:
Break;
}

Return true;
} In fact, there are not many codes. You can basically understand them. If you want to use the source code, please leave a message and take the time to write your own learning code. I hope it will help you.

From the column kangkangz4