Changeset 461

Timestamp:

Jun 5, 2006, 6:42:59 PM (18 years ago)

Author:

mmc

Message:

Fixed a bug in the BMP encoding of the transmitted image. BMP wants
all data in BGR (backwards) form, and it pads each scan line to an
even multiple of 4 bytes. The OpenGL calls that fetch the screen
do the same padding, but they put out data in RGB. We needed to
swap the bytes and communicate the proper padding information for
screen sizes that weren't an even multiple of 4.

File:

• trunk/gui/vizservers/nanovis/nanovis.cpp (modified) (6 diffs)

trunk/gui/vizservers/nanovis/nanovis.cpp

@@ -2178 +2178 @@
 
 
+#if DO_RLE
 char rle[512*512*3];
 int rle_size;
@@ -2211 +2212 @@
   }
 }
+#endif
 
 // used internally to build up the BMP file header
@@ -2231 +2233 @@
     header[pos++] = 'M';
 
+    // BE CAREFUL:  BMP files must have an even multiple of 4 bytes
+    // on each scan line.  If need be, we add padding to each line.
+    int pad = 0;
+    if ((3*win_width) % 4 > 0) {
+        pad = 4 - ((3*win_width) % 4);
+    }
+
     // file size in bytes
-    int fsize = win_width*win_height*3 + sizeof(header);
+    int fsize = (3*win_width+pad)*win_height + sizeof(header);
     bmp_header_add_int(header, pos, fsize);
 
@@ -2250 +2259 @@
     bmp_header_add_int(header, pos, win_height);
 
-    // 1 plane + 24 bits/pixel << 16
+    // 1 plane + (24 bits/pixel << 16)
     bmp_header_add_int(header, pos, 1572865);
 
@@ -2269 +2278 @@
 
     // BE CAREFUL: BMP format wants BGR ordering for screen data
-    for (int i=0; i < 3*win_width*win_height; i += 3) {
-        unsigned char tmp = screen_buffer[i+2];
-        screen_buffer[i+2] = screen_buffer[i];
-        screen_buffer[i] = tmp;
+    unsigned char* scr = screen_buffer;
+    for (int row=0; row < win_height; row++) {
+        for (int col=0; col < win_width; col++) {
+            unsigned char tmp = scr[2];
+            scr[2] = scr[0];  // B
+            scr[0] = tmp;     // R
+            scr += 3;
+        }
+        scr += pad;  // skip over padding already in screen data
     }
 
@@ -2280 +2294 @@
 
     write(0, header, sizeof(header));
-    write(0, screen_buffer, 3*win_width*win_height);
+    write(0, screen_buffer, (3*win_width+pad)*win_height);
 }