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glfont.cpp: add an internal class that uses Pango

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This commit is contained in:
Rudolf Polzer 2010-11-16 14:07:06 +01:00
parent 08f58dfd1f
commit a9e31a3db5
1 changed files with 139 additions and 0 deletions
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139
libs/gtkutil/glfont.cpp
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@ -157,3 +157,142 @@ void glfont_release(GLFont& font)
font = GLFont(0, 0, 0, 0);
}
#endif
// new font code ripped from ZeroRadiant (not in use yet)
#include <pango/pangoft2.h>
#include "igl.h"
class GLFontInternal
{
const char *font_string;
int font_height;
int font_ascent;
int font_descent;
int y_offset_bitmap_render_pango_units;
PangoContext *ft2_context;
public:
GLFontInternal(const char *_font_string): font_string(font_string)
{
PangoFontDescription *font_desc;
PangoLayout *layout;
PangoRectangle log_rect;
int font_ascent_pango_units;
int font_descent_pango_units;
// 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_context_set_font_description(ft2_context, font_desc);
pango_font_description_free(font_desc);
layout = pango_layout_new(ft2_context);
#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);
font_height = font_ascent + font_descent;
y_offset_bitmap_render_pango_units = (font_ascent * PANGO_SCALE) - font_ascent_pango_units;
}
~GLFontInternal()
{
g_object_unref(G_OBJECT(ft2_context));
}
// 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 printString(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;
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);
GlobalOpenGL().m_glGetFloatv(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.
GlobalOpenGL().m_glGetIntegerv(GL_UNPACK_ALIGNMENT, &previous_unpack_alignment);
previous_blend_enabled = GlobalOpenGL().m_glIsEnabled(GL_BLEND);
GlobalOpenGL().m_glGetIntegerv(GL_BLEND_SRC, &previous_blend_func_src);
GlobalOpenGL().m_glGetIntegerv(GL_BLEND_DST, &previous_blend_func_dst);
GlobalOpenGL().m_glGetFloatv(GL_RED_BIAS, &previous_red_bias);
GlobalOpenGL().m_glGetFloatv(GL_GREEN_BIAS, &previous_green_bias);
GlobalOpenGL().m_glGetFloatv(GL_BLUE_BIAS, &previous_blue_bias);
GlobalOpenGL().m_glGetFloatv(GL_ALPHA_SCALE, &previous_alpha_scale);
GlobalOpenGL().m_glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
GlobalOpenGL().m_glEnable(GL_BLEND);
GlobalOpenGL().m_glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
GlobalOpenGL().m_glPixelTransferf(GL_RED_BIAS, color[0]);
GlobalOpenGL().m_glPixelTransferf(GL_GREEN_BIAS, color[1]);
GlobalOpenGL().m_glPixelTransferf(GL_BLUE_BIAS, color[2]);
GlobalOpenGL().m_glPixelTransferf(GL_ALPHA_SCALE, color[3]);
GlobalOpenGL().m_glDrawPixels(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.
GlobalOpenGL().m_glPixelTransferf(GL_ALPHA_SCALE, previous_alpha_scale);
GlobalOpenGL().m_glPixelTransferf(GL_BLUE_BIAS, previous_blue_bias);
GlobalOpenGL().m_glPixelTransferf(GL_GREEN_BIAS, previous_green_bias);
GlobalOpenGL().m_glPixelTransferf(GL_RED_BIAS, previous_red_bias);
GlobalOpenGL().m_glBlendFunc(previous_blend_func_src, previous_blend_func_dst);
if (!previous_blend_enabled) { GlobalOpenGL().m_glDisable(GL_BLEND); }
GlobalOpenGL().m_glPixelStorei(GL_UNPACK_ALIGNMENT, previous_unpack_alignment);
}
g_object_unref(G_OBJECT(layout));
}
};