Android Color Rendering (vii) Radialgradient loop rendering for water ripple effect

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

What can we do with circular rendering? In fact, many are very common, such as the help of the previous implementation of the sugar effect, colored hot air balloon, such as here to talk about the water ripple effect, or can also be understood as a diffuse color rendering effect

First Look at:

Touch the screen to see the corresponding effect, you can see, to achieve this effect, the use of radialgradient, just a few simple lines of code:

Mainactivity:

[Java]View PlainCopy

2. Package com.tony.testshader;
6. Import Android.os.Bundle;
8. Import android.app.Activity;
10. Import Android.graphics.Bitmap;
12. Import Android.graphics.BitmapFactory;
14. Import Android.view.Menu;
16. Import Android.widget.SeekBar;
18. Import Android.widget.SeekBar.OnSeekBarChangeListener;
22. Public class Mainactivity extends Activity implements onseekbarchangelistener{
26. private Waterripplesview Waterripplesview;
34. @Override
36. protected void OnCreate (Bundle savedinstancestate) {
38. super.oncreate (savedinstancestate);
44. Waterripplesview = New Waterripplesview (this);
46. Setcontentview (Waterripplesview);
48. }
52. @Override
54. Public Boolean oncreateoptionsmenu (Menu menu) {
56. Getmenuinflater (). Inflate (R.menu.main, menu);
58. return true;
60. }
68. }

Waterripplesview:

[Java]View PlainCopy

2. Package com.tony.testshader;
6. Import Android.content.Context;
8. Import Android.graphics.Bitmap;
10. Import Android.graphics.BitmapShader;
12. Import Android.graphics.Canvas;
14. Import Android.graphics.Color;
16. Import Android.graphics.Paint;
18. Import android.graphics.RadialGradient;
20. Import Android.graphics.Shader;
22. Import android.graphics.drawable.BitmapDrawable;
24. Import android.graphics.drawable.ShapeDrawable;
26. Import Android.graphics.drawable.shapes.OvalShape;
28. Import Android.util.AttributeSet;
30. Import Android.util.DisplayMetrics;
32. Import android.view.MotionEvent;
34. Import Android.view.View;
36. /**
38. * Water Ripple Effect
40. * @author Tony
42. *
44. */
48. public class Waterripplesview extends View {
52. Shader mbitmapshader = null;
54. Bitmap mbitmappn = null;
56. Paint mpaint = null;
58. Shader mradialgradient = null;
60. Canvas Mcanvas = null;
62. shapedrawable mshapedrawable = null;
66. Public Waterripplesview (context context) {
68. super (context);
72. //initialization work
74. Bitmap bitmaptemp = ((bitmapdrawable) getresources (). Getdrawable (
76. r.drawable.leaf)). Getbitmap ();
78. Displaymetrics DM = getresources (). Getdisplaymetrics ();
80. //Create a picture that matches the size of the currently used device window
82. MBITMAPPN = Bitmap.createscaledbitmap (Bitmaptemp, Dm.widthpixels,
84. Dm.heightpixels, true);
86. //Create Bitmapshader Object
88. Mbitmapshader = New Bitmapshader (Mbitmappn, Shader.TileMode.REPEAT,
90. Shader.TileMode.MIRROR);
92. Mpaint = new Paint ();
94. }
98. Public Waterripplesview (context context, AttributeSet attrs) {
100. Super (context, attrs);
102. }
106. @Override
108. protected void OnDraw (canvas canvas) {
110. //TODO auto-generated method stub
112. Super.ondraw (canvas);
116. //Crop the picture to an oval shape
118. //Create a Shapedrawable object and define the shape as an ellipse
120. mshapedrawable = New Shapedrawable (new OvalShape ()); OvalShape: Oval
122. //Set the ellipse to draw something for shapedrawable picture
124. Mshapedrawable.getpaint (). Setshader (Mbitmapshader);
126. //Set display area
128. Mshapedrawable.setbounds (0, 0, Mbitmappn.getwidth (),
130. Mbitmappn.getheight ());
132. //Draw shapedrawable
134. Mshapedrawable.draw (canvas);
136. if (mradialgradient! = null) {
138. Mpaint.setshader (mradialgradient);
140. Canvas.drawcircle (0, 0, mpaint);
142. }
146. }
150. //@ Overwrite touch screen event
152. Public Boolean ontouchevent (Motionevent event) {
154. //@ Set alpha channel (transparency)
156. Mpaint.setalpha (400);
158. Mradialgradient = New Radialgradient (Event.getx (), Event.gety (),
160. new int[] {color.white, color.transparent},null, Shader.TileMode.REPEAT);
162. //@ Redraw
164. Postinvalidate ();
166. return true;
168. }
172. }

Android Color Rendering (vii) Radialgradient loop rendering for water ripple effect