AGG第四十一课AGG和GDI渲染字体大小对比
如下是GDI渲染字体的代码：
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CClientDC dc(this);
CPen pen(PS_SOLID,3,RGB(0,255,255));
CPen* pOldPen;
pOldPen=dc.SelectObject (&pen);
dc.SelectObject (&pOldPen);
CFont font;
CFont* pOLdFont = NULL;
font.CreatePointFont(10,_T("System"),&dc);
pOLdFont = dc.SelectObject(&font);
dc.SetBkMode(TRANSPARENT);
dc.TextOut(1074 - 100, 800 - 293, _T("A"));
dc.SelectObject(pOLdFont);
font.DeleteObject();
font.CreatePointFont(100,_T("System"),&dc);
pOLdFont = dc.SelectObject(&font);
dc.SetBkMode(TRANSPARENT);
dc.TextOut(1074 - 90, 800 - 280, _T("A"));
dc.SelectObject(pOLdFont);
font.DeleteObject();
结论：发现字体的高度最小为100，设置其他的最小值，字体没有发生改变。
如下是AGG渲染字体大小的代码：
void RenderTestByGsv()
{
agg::rendering_buffer &rbuf = rbuf_window();
agg::pixfmt_bgr24 pixf(rbuf);
typedef agg::renderer_base
renderer_base_type renb(pixf);
typedef agg::renderer_scanline_aa_solid
renderder_scanline_type rensl(renb);
agg::rasterizer_scanline_aa<> ras;
agg::scanline_u8 sl;
ras.reset();
agg::gsv_text text;
text.text("123ABC");
text.size(10, 8);
text.flip(true);
text.start_point(150,150);
agg::trans_affine mtx;
mtx.reset();
agg::gsv_text_outline
text_p.width(1.0);
rensl.color(agg::rgba(0.0, 0.0, 0.0));
ras.add_path(text_p, 0);
agg::render_scanlines_aa_solid(ras,sl,renb,agg::rgba8(255,0,0));
}
邮件原文：
This is going to come off as a smart-ass reply, and I don't intend it to be.
If agg doesn't work well with small fonts, why not just use GDI in those
cases? Its easy to have a single buffer that can be operated on by both agg
and gdi.
if (font_height < 10)
{
renderWithGdi()
}
else
{
renderWithAgg()
}
Since I am bothering everybody today, I am wondering about rendering small
true type fonts.
When the font height gets below 10 or so, Windows draws the font with
vectors. This keeps the characters readable as the font gets smaller.
With AGG I'm using outlines, and that tends to "smoosh" the characters
together.
I've set the contour width to 0.01, and even 0.0, but when the fonts get
small, the characters Become unreadable. More so, when displaying Kanji.
What I'd like to do is to figure out a way to force the glyphs to be drawn
as vector's (like GDI).
I want to keep using glyph_ren_outline, as I can rotate and scale the
results nicely.
Any Ideas?
Here is a simple version of code that I use (I removed extra stuff):
//
// feng is create before as font_engine_win32_tt_int32 // typedef
agg::conv_contour
contour_type; typedef agg::conv_curve
curve_type;
typedef agg::font_cache_manager
font_manager_type;
font_manager_type fman(feng);
curve_type curves(fman.path_adaptor());
contour_type contour(curves);
//
//Draw Text Routine
//
agg::rasterizer_scanline_aa<> ras;
agg::scanline_u8 sl;
agg::glyph_rendering gren = agg::glyph_ren_outline;
agg::path_storage path;
agg::conv_stroke
agg::trans_affine mtx;
mtx *= agg::trans_affine_translation(-x, -y); mtx *=
agg::trans_affine_rotation(-1.0 * rotation ); mtx *=
agg::trans_affine_translation(x, y);
feng.char_set( SHIFTJIS_CHARSET );
if(m_feng.create_font( "MS GOTHIC", gren ))
{
feng.weight( 100 ); // FW_LIGHT == 300
contour.width( 0.01 );
font_trans_type ftrans( contour, mtx );
const char *pp = pString;
const agg::glyph_cache *glyph;
while(*pp)
{
if(isJIS(pp)) // Check for Multibtye Japanese String
{
WCHAR ws[2];
MultiByteToWideChar( 932, 0, pp, 2, ws, sizeof(ws));
glyph = pT->m_fman.glyph(ws[0]);
++pp;// Multi byte
}
else
{
glyph = pT->m_fman.glyph(*pp);
}
pp++;
if(glyph)
{
ras.reset();
ras.add_path(ftrans);
fman.add_kerning(&x, &y);
agg::render_scanlines(ras, sl, ren_aa);
x += glyph->advance_x;
y += glyph->advance_y;
}
}
}
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