Learning notes for Android

<1> Introduction

This is a very dazzling effect. You can drag the image with your fingers to move it. The iPhone once attracted countless Apple fans with this special effect, which can also be achieved on the Android platform.

To achieve this, you must have a container to store the image requested by Gallery. Here, we use a derived class inherited from baseadapter to install these images. We need to listen to the setonitemclicklistener event to determine the image selected currently.

First, we need to store the index of the displayed image in an int array. Then, you can use the setimageresource method to set the image resources to be displayed in the imageview. Finally, the imageview of each image is displayed on the screen.

 

<2> XML attributes

 

Attribute name	Description
Android: animationduration	Set the time required for converting the animation when the layout changes (in milliseconds ). Timing only when the animation starts. The value must be an integer, such as 100.
Android: gravity	Specifies how to place content on the X and Y axes of an object. Specify one or more constants (separated by "|) Constant Value Description Top 0x30 Close to the Container top without changing its size Bottom 0x50 Close to the bottom of the container without changing its size Left 0x03 Close to the left side of the container without changing its size Right 0x05 Close to the right of the container without changing its size Center_vertical 0x10 Center vertically without changing its size Fill_vertical 0x70 Stretch vertically to filled containers Center_horizontal 0x01 Center horizontally without changing its size Fill_horizontal 0x07 Horizontally stretch to fill the container Center 0x11 Center alignment without changing its size Fill 0x77 Stretch horizontally and vertically to fill the container Clip_vertical 0x80 Vertical cutting (when the object edge exceeds the container, cut out the upper and lower edges) Clip_horizontal 0x08 Horizontal cut (when the object edge exceeds the container, cut out the left and right edges beyond the container)
Android: spacing	(Translator's note: Set the spacing between images)
Android: unselectedalpha	Sets the transparency (alpha) of unselected items ). The value must be of the float type, for example, "1.2 ".

 

<3> example

 

Package xiaosi. gallery; import android. app. activity; import android. content. context; import android. OS. bundle; import android. view. view; import android. view. viewgroup; import android. widget. adapterview; import android. widget. adapterview. onitemclicklistener; import android. widget. baseadapter; import android. widget. gallery; import android. widget. imageview; import android. widget. toast; public class galleryactivit Y extends activity {/** called when the activity is first created. */private gallery = NULL; @ override public void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. main); gallery = (Gallery) findviewbyid (R. id. gallery); // sets the image adapter Gallery. setadapter (New imageadapter (this); Gallery. setspacing (10); // sets the listener Gallery. setonitemclicklistener (New oni Temclicklistener () {public void onitemclick (adapterview <?> Arg0, view arg1, int arg2, long arg3) {toast. maketext (galleryactivity. this, "click the" + arg2 + "image", toast. length_long ). show () ;}}) ;}} class imageadapter extends baseadapter {private context; // image source array private integer [] imageinteger = {R. drawable. a, R. drawable. b, R. drawable. c, R. drawable. d, R. drawable. e, R. drawable. f ,}; public imageadapter (context c) {context = C ;}// obtain the number of images public int getcount () {return imageinteger. length ;}// obtain the position of the image in the library public object getitem (INT position) {return position ;}// obtain the image ID public long getitemid (INT position) {return position ;} public View getview (INT position, view convertview, viewgroup parent) {imageview = new imageview (context); // set the imageview resource for imageview. setimageresource (imageinteger [position]); // sets the display ratio type imageview. setscaletype (imageview. scaletype. fit_xy); // set the layout image 120*80 imageview. setlayoutparams (new gallery. layoutparams (120, 80); Return imageview ;}}

Main. xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" ><Gallery    android:id="@+id/gallery"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:gravity="bottom"        android:background="?android:galleryItemBackground"/></LinearLayout>