[Android] accesses and operates bitmap elements via JNI, supporting RGB565 and ARGB8888

 [Android] accesses and operates bitmap elements via JNI, supporting RGB565 and ARGB8888Tags: androidbitmapjni2014-05-09 20:35 2985 People read Comments (1) favorite reports

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

A simple JNI example, the input is bitmap (need to be mutable), the result is to turn bitmap into a grayscale image.

In order to look a bit of value, so at the same time support RGB565 and ARGB8888 (囧RZ)

[CPP]View Plaincopy

2. #include <stdio.h>
4. #include <stdlib.h>
6. #include <string.h>
8. #include <stdint.h>
10. #include <jni.h>
12. #include <android/bitmap.h>
14. #include <android/log.h>
18. #ifndef eprintf
20. #define EPRINTF (...) __android_log_print (Android_log_error, "@", __va_args__)
22. #endif
26. #define RGB565_R (P) ((((p) & 0xf800) >> one) << 3)
28. #define RGB565_G (P) ((((p) & 0X7E0) >> 5) << 2)
30. #define RGB565_B (P) (((p) & 0x1F) << 3)
32. #define MAKE_RGB565 (R,g,b) (((R) >> 3) << 11) | (((g) >> 2) << 5) | ((b) >> 3))
36. #define RGBA_A (P) (((p) & 0xff000000) >> 24)
38. #define RGBA_R (P) (((p) & 0x00ff0000) >> 16)
40. #define RGBA_G (P) (((p) & 0x0000FF00) >> 8)
42. #define RGBA_B (P) ((p) & 0X000000FF)
44. #define MAKE_RGBA (R,g,b,a) (((a) << 24) | (r) << 16) | ((g) << 8) | (b))
48. Jniexport void Jnicall java_com_yxcorp_hello_effect_update
50. (JNIEnv *env, Jclass clazz, Jobject zbitmap) {
52. JNIEnv J = *env;
56. if (Zbitmap = = NULL) {
58. eprintf ("bitmap is null\n");
60. return;
62. }
66. //Get bitmap Info
68. Androidbitmapinfo info;
70. memset (&info, 0, sizeof (info));
72. Androidbitmap_getinfo (env, Zbitmap, &info);
74. //Check format, only RGB565 & RGBA is supported
76. if (info.width <= 0 | | info.height <= 0 | |
78. (Info.format! = android_bitmap_format_rgb_565 && Info.format! = android_bitmap_format_rgba_8888)) {
80. eprintf ("Invalid bitmap\n");
82. J->thrownew (env, J->findclass (env, "Java/io/ioexception"), "Invalid Bitmap");
84. return;
86. }
90. //Lock the bitmap to get the buffer
92. void * pixels = NULL;
94. int res = androidbitmap_lockpixels (env, Zbitmap, &pixels);
96. if (pixels = = NULL) {
98. eprintf ("fail to lock Bitmap:%d\n", res);
100. J->thrownew (env, J->findclass (env, "Java/io/ioexception"), "fail to open bitmap");
102. return;
104. }
108. eprintf ("Effect:%dx%d,%d\n", Info.width, Info.height, Info.format);
112. int x = 0, y = 0;
114. //From top to bottom
116. For (y = 0; y < info.height; ++y) {
118. // from left to right
120. For (x = 0; x < info.width; ++x) {
122. int a = 0, r = 0, g = 0, b = 0;
124. void *pixel = NULL;
126. //Get each pixel by format
128. if (Info.format = = android_bitmap_format_rgb_565) {
130. Pixel = ((uint16_t *) pixels) + y * info.width + x;
132. uint16_t v = * (uint16_t *) pixel;
134. R = Rgb565_r (v);
136. g = Rgb565_g (v);
138. b = Rgb565_b (v);
140. } else {//RGBA
142. Pixel = ((uint32_t *) pixels) + y * info.width + x;
144. uint32_t v = * (uint32_t *) pixel;
146. A = Rgba_a (v);
148. R = Rgba_r (v);
150. g = Rgba_g (v);
152. b = Rgba_b (v);
154. }
158. //Grayscale
160. int Gray = (R * + G * + + b *) >> 7;
164. //Write the pixel back
166. if (Info.format = = android_bitmap_format_rgb_565) {
168. * ((uint16_t *) pixel) = make_rgb565 (Gray, Gray, gray);
170. } else {//RGBA
172. * ((uint32_t *) pixel) = Make_rgba (Gray, Gray, Gray, a);
174. }
176. }
178. }
182. Androidbitmap_unlockpixels (env, ZBITMAP);
184. }

[Android] accesses and operates bitmap elements via JNI, supporting RGB565 and ARGB8888