Android handout 2: simple image browser with screenshot effect (for imageview)

Layout highlights:

// Distance from the bottom of the previous control

Android: layout_margintop = "10dp"

CodePhase Analysis:

// Return the printable view and convert it down to the printable view of Bitmap.

Bitmapdrawable = (bitmapdrawable) image1.getdrawable ();

// If the image has not been recycled, forcibly recycle the image first.

If (! Bitmapdrawable. getbitmap (). isrecycled ())
{
Bitmapdrawable. getbitmap (). Recycle ();
}

// Change the image displayed in the imageview
Image1.setimagebitmap (bitmapfactory. decoderesource (getresources (), images [++ currentimg]);

// Capture the original image for display

1. Use setontouchlistener to listen

2. Obtain the screen width for obtaining the actual proportion in step 3.

Displaymetrics dm = new displaymetrics ();
Getwindowmanager (). getdefaultdisplay (). getmetrics (DM );
System. Out. println (DM. widthpixels );

3. ObtainThe actual bitmap image size and the scaling ratio of the first imageview

Double scale = bitmap. getwidth ()/DM. widthpixels;

4. Get the start point of the image to be displayed

Int x = (INT) (event. getx () * scale );
Int y = (INT) (event. Gety () * scale );

5.AlgorithmThe specified start point and display area cannot be greater than the image area

If (x + 120> bitmap. getwidth ())
{
X = bitmap. getwidth ()-120;
}
If (Y + 120> bitmap. getheight ())
{
Y = bitmap. getheight ()-120;
}

6. display the specified area of the image
Image2.setimagebitmap (bitmap. createbitmap (bitmap, X, Y, 120,120 ));