Android Metro Style Launcher Development series The second article

Objective:

Dear friends, please forgive me for so long to start writing this series of the second blog, no way to busy new product release, good nonsense not to say, first review: In my previous blog http://www.cnblogs.com/2010wuhao/p/4363041. html wrote how to configure the Android development environment, just with text and pictures to show the development of Metro style Launcher preliminary design and product requirements, this article will be on the code to explain how to achieve the corresponding UI effect, OK, storytelling!

Launcher Main Framework implementation:

Launcher Main Frame I choose is familiar with the Viewpager control, because Viewpager can easily do pager between the switch animation, animation can be customized, so easy to get rid of the various effects slide out of the screen, you can also control the speed of switching, This makes it easy to achieve the following effects:

1. sliding speed control:
   

   This is done by getting Viewpager's scroller, setting some parameters on Scroller, and implementing the Code as follows:

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   field Scroller = Viewpager. class .getdeclaredfield ( scroller.setaccessible ( true interpolator interpolator =  new  linearinterpolator (); //set accelerator viewpagerscroller scroller =  new  viewpagerscroller (context,interpolator); //Reset Viewpager scroller scroller.set ( this

   In the above code is used in the Viewpagerscroller.java, in the Viewpagerscroller is set as follows, where the mduration variable is a custom animation time, this you can set the length of time according to their own animation effect, I define this as 500 milliseconds.

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   @OverridepublicvoidstartScroll(intstartX, intstartY, intdx, intdy) {    // Ignore received duration, use fixed one instead    super.startScroll(startX, startY, dx, dy, mDuration);}@OverridepublicvoidstartScroll(intstartX, intstartY, intdx, intdy, intduration) {    // Ignore received duration, use fixed one instead    super.startScroll(startX, startY, dx, dy, mDuration);}

2. The switch effect between page is implemented:
   Each screen page between the switch is implemented by implementing the Viewpager.pagetransformer interface, the specific explanation of this interface I do not introduce here, you can refer to Google official documents: Using Viewpager for screen Slides. My implementation is as follows:
   

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   classLauncherPageTransformer implementsViewPager.PageTransformer {    privatestaticfloatDEFAULT_SCALE = 1.0f;    privatestaticfloatSCALE_FACTOR = 0.30f;// 缩放因子 0.50f    privatestaticfloatROTATION_FACTOR = 20f;// 旋转因子    privatestaticfloatALPHA_FACTOR = 0.8f;    @Override    publicvoidtransformPage(View view, floatposition) {        if(position <= 1) { // [-1,1]            // Modify the default slide transition to shrink the page as well            if(position < 0) {                // view.setRotationY(position * ROTATION_FACTOR);                view.setScaleX(SCALE_FACTOR * position + DEFAULT_SCALE);                view.setScaleY(SCALE_FACTOR * position + DEFAULT_SCALE);                // view.setAlpha(ALPHA_FACTOR * position + 1.0f);            } else{                // view.setRotationY(position * ROTATION_FACTOR);                view.setScaleX(SCALE_FACTOR * -position + DEFAULT_SCALE);                view.setScaleY(SCALE_FACTOR * -position + DEFAULT_SCALE);                // view.setAlpha(ALPHA_FACTOR * -position + 1.0f);            }        }    }}

   　　
   Specific effects can be achieved by modifying the rotation and scaling.

3. left and right side page hover implementation：
   

   The page section on both sides of the Home screen page can be implemented by setting the Viewpager setpagemargin (int margin) method, with the following code:

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   publicclassLauncherViewPager extendsViewPager {    publicstaticfinalintPAGE_LIMIT = 3;    publicLauncherViewPager(Context context) {        this(context, null);    }    publicLauncherViewPager(Context context, AttributeSet attrs) {        super(context, attrs);        init(context);    }    privatevoidinit(Context context) {        this.setPageMargin(-getResources().getInteger(R.integer.portal_viewpager_margin));        this.setOffscreenPageLimit(PAGE_LIMIT);        this.setPageTransformer(true, newLauncherPageTransformer());        try {            Field Scroller = ViewPager.class.getDeclaredField("mScroller");            Scroller.setAccessible(true);            Interpolator interpolator = new LinearInterpolator();            ViewPagerScroller scroller = newViewPagerScroller(context,                    interpolator);            Scroller.set(this, scroller);        } catch(NoSuchFieldException e) {        } catch(IllegalArgumentException e) {        } catch(IllegalAccessException e) {        }    }}

5. Summarize:
   The above is the launcher main frame using Viewpager to achieve left and right slide and zoom effect explanation, write bad place also please point out and criticize, "three people will have my teacher", any criticism and suggestions I will have to reply and exchange, can add my number, faster communication. Next blog I will explain each of the screen Cellview implementation, with focus amplification effect, to achieve each focus of the cellview suspension effect and in the XML file flexible configuration links and so on.
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Android Metro Style Launcher Development series The second article