-void gtk_glwidget_create_font(){
- PangoFontDescription *font_desc;
- PangoLayout *layout;
- PangoRectangle log_rect;
- int font_ascent_pango_units;
- int font_descent_pango_units;
-
- if ( _debug_font_created ) {
- Error( "Programming error: gtk_glwidget_create_font() was already called; "
- "you must call gtk_glwidget_destroy_font() before creating font again" );
- }
- _debug_font_created = 1;
-
- // This call is deprecated so we'll have to fix it sometime.
- ft2_context = pango_ft2_get_context( 72, 72 );
-
- font_desc = pango_font_description_from_string( font_string );
- pango_font_description_set_size( font_desc, font_height * PANGO_SCALE );
- pango_context_set_font_description( ft2_context, font_desc );
- pango_font_description_free( font_desc );
-
- layout = pango_layout_new( ft2_context );
-
- // I don't believe that's standard preprocessor syntax?
-#if !PANGO_VERSION_CHECK( 1,22,0 )
- PangoLayoutIter *iter;
- iter = pango_layout_get_iter( layout );
- font_ascent_pango_units = pango_layout_iter_get_baseline( iter );
- pango_layout_iter_free( iter );
-#else
- font_ascent_pango_units = pango_layout_get_baseline( layout );
-#endif
-
- pango_layout_get_extents( layout, NULL, &log_rect );
- g_object_unref( G_OBJECT( layout ) );
- font_descent_pango_units = log_rect.height - font_ascent_pango_units;
-
- font_ascent = PANGO_PIXELS_CEIL( font_ascent_pango_units );
- font_descent = PANGO_PIXELS_CEIL( font_descent_pango_units );
- y_offset_bitmap_render_pango_units = ( font_ascent * PANGO_SCALE ) - font_ascent_pango_units;
-}
-
-void gtk_glwidget_destroy_font(){
- if ( !_debug_font_created ) {
- Error( "Programming error: gtk_glwidget_destroy_font() called when font "
- "does not exist" );
- }
-
- font_ascent = -1;
- font_descent = -1;
- y_offset_bitmap_render_pango_units = -1;
- g_object_unref( G_OBJECT( ft2_context ) );
- _debug_font_created = 0;
-}
-
-
-// Renders the input text at the current location with the current color.
-// The X position of the current location is used to place the left edge of the text image,
-// where the text image bounds are defined as the logical extents of the line of text.
-// The Y position of the current location is used to place the bottom of the text image.
-// You should offset the Y position by the amount returned by gtk_glwidget_font_descent()
-// if you want to place the baseline of the text image at the current Y position.
-// Note: A problem with this function is that if the lower left corner of the text falls
-// just a hair outside of the viewport (meaning the current raster position is invalid),
-// then no text will be rendered. The solution to this is a very hacky one. You can search
-// Google for "glDrawPixels clipping".
-void gtk_glwidget_print_string( const char *s ){
- // The idea for this code initially came from the font-pangoft2.c example that comes with GtkGLExt.
-
- PangoLayout *layout;
- PangoRectangle log_rect;
- FT_Bitmap bitmap;
- unsigned char *begin_bitmap_buffer;
- GLfloat color[4];
- GLint previous_unpack_alignment;
- GLboolean previous_blend_enabled;
- GLint previous_blend_func_src;
- GLint previous_blend_func_dst;
- GLfloat previous_red_bias;
- GLfloat previous_green_bias;
- GLfloat previous_blue_bias;
- GLfloat previous_alpha_scale;
-
- if ( !_debug_font_created ) {
- Error( "Programming error: gtk_glwidget_print_string() called but font does not exist; "
- "you should have called gtk_glwidget_create_font() first" );
- }
-
- layout = pango_layout_new( ft2_context );
- pango_layout_set_width( layout, -1 ); // -1 no wrapping. All text on one line.
- pango_layout_set_text( layout, s, -1 ); // -1 null-terminated string.
- pango_layout_get_extents( layout, NULL, &log_rect );
-
- if ( log_rect.width > 0 && log_rect.height > 0 ) {
- bitmap.rows = font_ascent + font_descent;
- bitmap.width = PANGO_PIXELS_CEIL( log_rect.width );
- bitmap.pitch = -bitmap.width; // Rendering it "upside down" for OpenGL.
- begin_bitmap_buffer = (unsigned char *) g_malloc( bitmap.rows * bitmap.width );
- memset( begin_bitmap_buffer, 0, bitmap.rows * bitmap.width );
- bitmap.buffer = begin_bitmap_buffer + ( bitmap.rows - 1 ) * bitmap.width; // See pitch above.
- bitmap.num_grays = 0xff;
- bitmap.pixel_mode = FT_PIXEL_MODE_GRAY;
- pango_ft2_render_layout_subpixel( &bitmap, layout, -log_rect.x,
- y_offset_bitmap_render_pango_units );
- qglGetFloatv( GL_CURRENT_COLOR, color );
-
- // Save state. I didn't see any OpenGL push/pop operations for these.
- // Question: Is saving/restoring this state necessary? Being safe.
- qglGetIntegerv( GL_UNPACK_ALIGNMENT, &previous_unpack_alignment );
- previous_blend_enabled = qglIsEnabled( GL_BLEND );
- qglGetIntegerv( GL_BLEND_SRC, &previous_blend_func_src );
- qglGetIntegerv( GL_BLEND_DST, &previous_blend_func_dst );
- qglGetFloatv( GL_RED_BIAS, &previous_red_bias );
- qglGetFloatv( GL_GREEN_BIAS, &previous_green_bias );
- qglGetFloatv( GL_BLUE_BIAS, &previous_blue_bias );
- qglGetFloatv( GL_ALPHA_SCALE, &previous_alpha_scale );
-
- qglPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
- qglEnable( GL_BLEND );
- qglBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
- qglPixelTransferf( GL_RED_BIAS, color[0] );
- qglPixelTransferf( GL_GREEN_BIAS, color[1] );
- qglPixelTransferf( GL_BLUE_BIAS, color[2] );
- qglPixelTransferf( GL_ALPHA_SCALE, color[3] );
-
- qglDrawPixels( bitmap.width, bitmap.rows,
- GL_ALPHA, GL_UNSIGNED_BYTE, begin_bitmap_buffer );
- g_free( begin_bitmap_buffer );
-
- // Restore state in reverse order of how we set it.
- qglPixelTransferf( GL_ALPHA_SCALE, previous_alpha_scale );
- qglPixelTransferf( GL_BLUE_BIAS, previous_blue_bias );
- qglPixelTransferf( GL_GREEN_BIAS, previous_green_bias );
- qglPixelTransferf( GL_RED_BIAS, previous_red_bias );
- qglBlendFunc( previous_blend_func_src, previous_blend_func_dst );
- if ( !previous_blend_enabled ) {
- qglDisable( GL_BLEND );
- }
- qglPixelStorei( GL_UNPACK_ALIGNMENT, previous_unpack_alignment );
- }
-
- g_object_unref( G_OBJECT( layout ) );
-}
-
-void gtk_glwidget_print_char( char s ){
- char str[2];
- str[0] = s;
- str[1] = '\0';
- gtk_glwidget_print_string( str );
-}