Android Photoshop Palette App (ii) alphapatterndrawable of transparency drawing

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Android Photoshop Palette App (ii) alphapatterndrawable of transparency drawing

Here's how to implement the transparency selection bar in the PS palette. First of all, the main points:

1. The transparency selection bar is actually based on the selection of color bands between white (0xFFFFFFFF) and Gray (0XFFCBCBCB), which allows us to select a translucent color

2. The application can not only do the transparency color selection, but also can realize the translucent image effect in the application.

Here's a look at the code, mainly based on the drawable rewrite:

[Java]View PlainCopy

2. /*
4. * Copyright (C) Daniel Nilsson
6. *
8. * Licensed under the Apache License, Version 2.0 (the "License");
10. * You are not a use this file except in compliance with the License.
12. * Obtain a copy of the License at
14. *
16. * http://www.apache.org/licenses/LICENSE-2.0
18. *
20. * Unless required by applicable or agreed to writing, software
22. * Distributed under the License is distributed on a "as is" BASIS,
24. * Without warranties or CONDITIONS of any KIND, either express or implied.
26. * See the License for the specific language governing permissions and
28. * Limitations under the License.
30. */
34. Package net.margaritov.preference.colorpicker;
38. Import Android.graphics.Bitmap;
40. Import Android.graphics.Bitmap.Config;
42. Import Android.graphics.Canvas;
44. Import Android.graphics.ColorFilter;
46. Import Android.graphics.Paint;
48. Import Android.graphics.Rect;
50. Import android.graphics.drawable.Drawable;
54. /**
56. * This drawable, draws a simple white and gray chessboard pattern.
58. * It ' s pattern you'll often see as a background behind a
60. * Partly transparent image in many applications.
62. * @author Daniel Nilsson
64. */
66. Public class Alphapatterndrawable extends drawable {
70. private int mrectanglesize = 10;
74. private Paint Mpaint = new Paint ();
76. private Paint Mpaintwhite = new Paint ();
78. private Paint Mpaintgray = new Paint ();
82. private int numrectangleshorizontal;
84. private int numrectanglesvertical;
88. /** 
90. * Bitmap in which the pattern would be cahched.
92. */
94. private Bitmap Mbitmap;
98. Public alphapatterndrawable (int rectanglesize) {
100. Mrectanglesize = rectanglesize;
102. Mpaintwhite.setcolor (0xFFFFFFFF);
104. Mpaintgray.setcolor (0XFFCBCBCB);
106. }
110. @Override
112. public void Draw (canvas canvas) {
114. Canvas.drawbitmap (Mbitmap, null, getbounds (), mpaint);
116. }
120. @Override
122. public int getopacity () {
124. return 0;
126. }
130. @Override
132. public void Setalpha (int alpha) {
134. throw New Unsupportedoperationexception ("Alpha is not supported by this drawwable.");
136. }
140. @Override
142. public void Setcolorfilter (Colorfilter CF) {
144. throw New Unsupportedoperationexception ("Colorfilter is not supported by this drawwable.");
146. }
150. @Override
152. protected void Onboundschange (Rect bounds) {
154. Super.onboundschange (bounds);
158. int height = bounds.height ();
160. int width = bounds.width ();
164. Numrectangleshorizontal = (int) Math.ceil ((width/mrectanglesize));
166. numrectanglesvertical = (int) Math.ceil (height/mrectanglesize);
170. Generatepatternbitmap ();
174. }
178. /** 
180. * This would generate a bitmap with the pattern
182. * As big as the rectangle we were allow to draw on.
184. * We do this to chache the bitmap so We don ' t need to
186. * Recreate it each time draw () is called since it
188. * Takes a few milliseconds.
190. */
192. private void Generatepatternbitmap () {
196. if (getbounds (). Width () <= 0 | | getbounds (). Height () <= 0) {
198. return;
200. }
204. Mbitmap = Bitmap.createbitmap (GetBounds (). Width (), getbounds (). Height (), config.argb_8888);
206. Canvas canvas = new Canvas (MBITMAP);
210. Rect r = new Rect ();
212. Boolean verticalstartwhite = true;
214. For (int i = 0; I <= numrectanglesvertical; i++) {
218. Boolean iswhite = Verticalstartwhite;
220. For (int j = 0; J <= Numrectangleshorizontal; j + +) {
224. R.top = i * mrectanglesize;
226. R.left = J * mrectanglesize;
228. R.bottom = R.top + mrectanglesize;
230. R.right = R.left + mrectanglesize;
234. Canvas.drawrect (R, Iswhite Mpaintwhite:mpaintgray);
238. Iswhite =!iswhite;
240. }
244. Verticalstartwhite =!verticalstartwhite;
248. }
252. }
256. }

Android Photoshop Palette App (ii) alphapatterndrawable of transparency drawing