static void DrawBackground(void) {
// Whole window cleared with clear color, checkerboard rendered on top of it.
glClear(GL_COLOR_BUFFER_BIT);
DrawCheckerBoard();
// ANIM background color rendered (blend) on top. Default is white for still
// images (without ANIM chunk). glClear() can't be used for that (no blend).
if (kParams.draw_anim_background_color) {
glPushMatrix();
glLoadIdentity();
glColor4f(GetColorf(kParams.bg_color, 16), // BGRA from spec
GetColorf(kParams.bg_color, 8),
GetColorf(kParams.bg_color, 0),
GetColorf(kParams.bg_color, 24));
glRecti(-1, -1, +1, +1);
glPopMatrix();
}
}
static void StartDisplay(void) {
const int width = kParams.canvas_width;
const int height = kParams.canvas_height;
glutInitDisplayMode(GLUT_RGBA);
glutInitWindowSize(width, height);
glutCreateWindow("WebP viewer");
glutDisplayFunc(HandleDisplay);
glutIdleFunc(NULL);
glutKeyboardFunc(HandleKey);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glClearColor(GetColorf(kParams.bg_color, 0),
GetColorf(kParams.bg_color, 8),
GetColorf(kParams.bg_color, 16),
GetColorf(kParams.bg_color, 24));
HandleReshape(width, height);
glClear(GL_COLOR_BUFFER_BIT);
DrawCheckerBoard();
}
static void HandleDisplay(void) {
const WebPDecBuffer* const pic = kParams.pic;
const WebPIterator* const curr = &kParams.curr_frame;
WebPIterator* const prev = &kParams.prev_frame;
GLfloat xoff, yoff;
if (pic == NULL) return;
glPushMatrix();
glPixelZoom(1, -1);
xoff = (GLfloat)(2. * curr->x_offset / kParams.canvas_width);
yoff = (GLfloat)(2. * curr->y_offset / kParams.canvas_height);
glRasterPos2f(-1.f + xoff, 1.f - yoff);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glPixelStorei(GL_UNPACK_ROW_LENGTH, pic->u.RGBA.stride / 4);
if (prev->dispose_method == WEBP_MUX_DISPOSE_BACKGROUND ||
curr->blend_method == WEBP_MUX_NO_BLEND) {
// TODO(later): these offsets and those above should factor in window size.
// they will be incorrect if the window is resized.
// glScissor() takes window coordinates (0,0 at bottom left).
int window_x, window_y;
if (prev->dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
// Clear the previous frame rectangle.
window_x = prev->x_offset;
window_y = kParams.canvas_height - prev->y_offset - prev->height;
} else { // curr->blend_method == WEBP_MUX_NO_BLEND.
// We simulate no-blending behavior by first clearing the current frame
// rectangle (to a checker-board) and then alpha-blending against it.
window_x = curr->x_offset;
window_y = kParams.canvas_height - curr->y_offset - curr->height;
}
glEnable(GL_SCISSOR_TEST);
// Only update the requested area, not the whole canvas.
glScissor(window_x, window_y, prev->width, prev->height);
glClear(GL_COLOR_BUFFER_BIT); // use clear color
DrawCheckerBoard();
glDisable(GL_SCISSOR_TEST);
}
*prev = *curr;
glDrawPixels(pic->width, pic->height,
GL_RGBA, GL_UNSIGNED_BYTE,
(GLvoid*)pic->u.RGBA.rgba);
if (kParams.print_info) {
char tmp[32];
glColor4f(0.90f, 0.0f, 0.90f, 1.0f);
glRasterPos2f(-0.95f, 0.90f);
PrintString(kParams.file_name);
snprintf(tmp, sizeof(tmp), "Dimension:%d x %d", pic->width, pic->height);
glColor4f(0.90f, 0.0f, 0.90f, 1.0f);
glRasterPos2f(-0.95f, 0.80f);
PrintString(tmp);
if (curr->x_offset != 0 || curr->y_offset != 0) {
snprintf(tmp, sizeof(tmp), " (offset:%d,%d)",
curr->x_offset, curr->y_offset);
glRasterPos2f(-0.95f, 0.70f);
PrintString(tmp);
}
}
glPopMatrix();
glFlush();
}
static void HandleDisplay(void) {
const WebPDecBuffer* const pic = kParams.pic;
const WebPIterator* const iter = &kParams.frameiter;
GLfloat xoff, yoff;
if (pic == NULL) return;
glPushMatrix();
glPixelZoom(1, -1);
xoff = (GLfloat)(2. * iter->x_offset / kParams.canvas_width);
yoff = (GLfloat)(2. * iter->y_offset / kParams.canvas_height);
glRasterPos2f(-1.f + xoff, 1.f - yoff);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glPixelStorei(GL_UNPACK_ROW_LENGTH, pic->u.RGBA.stride / 4);
if (kParams.prev_frame.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
// TODO(later): these offsets and those above should factor in window size.
// they will be incorrect if the window is resized.
// glScissor() takes window coordinates (0,0 at bottom left).
const int window_x = kParams.prev_frame.x_offset;
const int window_y = kParams.canvas_height -
kParams.prev_frame.y_offset -
kParams.prev_frame.height;
glEnable(GL_SCISSOR_TEST);
// Only updated the requested area, not the whole canvas.
glScissor(window_x, window_y,
kParams.prev_frame.width, kParams.prev_frame.height);
glClear(GL_COLOR_BUFFER_BIT); // use clear color
DrawCheckerBoard();
glDisable(GL_SCISSOR_TEST);
}
kParams.prev_frame.width = iter->width;
kParams.prev_frame.height = iter->height;
kParams.prev_frame.x_offset = iter->x_offset;
kParams.prev_frame.y_offset = iter->y_offset;
kParams.prev_frame.dispose_method = iter->dispose_method;
glDrawPixels(pic->width, pic->height,
GL_RGBA, GL_UNSIGNED_BYTE,
(GLvoid*)pic->u.RGBA.rgba);
if (kParams.print_info) {
char tmp[32];
glColor4f(0.90f, 0.0f, 0.90f, 1.0f);
glRasterPos2f(-0.95f, 0.90f);
PrintString(kParams.file_name);
snprintf(tmp, sizeof(tmp), "Dimension:%d x %d", pic->width, pic->height);
glColor4f(0.90f, 0.0f, 0.90f, 1.0f);
glRasterPos2f(-0.95f, 0.80f);
PrintString(tmp);
if (iter->x_offset != 0 || iter->y_offset != 0) {
snprintf(tmp, sizeof(tmp), " (offset:%d,%d)",
iter->x_offset, iter->y_offset);
glRasterPos2f(-0.95f, 0.70f);
PrintString(tmp);
}
}
glPopMatrix();
glFlush();
}
