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GUI2/Canvas: handle text alpha as a render-time op

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This reduces the number of times the text itself needs to be rendered, especially for areas like the
story viewer where the only difference is alpha.
This commit is contained in:
Charles Dang 2017-07-15 01:44:49 +11:00
parent 3bf6768685
commit 1fd9a16a86
1 changed files with 13 additions and 1 deletions
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14
src/gui/core/canvas.cpp
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@ -1274,6 +1274,15 @@ void text_shape::draw(
return;
}
// Note about color handling. It's possible to render the text with alpha set directly
// but it results in unnecessary extra renders and cache storage. Instead, we save the
// provided alpha value and override the one passed to the rext renderer. Then, if the
// alpha isn't opaque, we set a texture alpha mod once the text is rendered.
color_t fg_color = color_(variables);
const uint8_t saved_alpha = fg_color.a;
fg_color.a = ALPHA_OPAQUE;
font::pango_text& text_renderer = font::get_text_renderer();
text_renderer
@ -1285,7 +1294,7 @@ void text_shape::draw(
.set_font_size(font_size_)
.set_font_style(font_style_)
.set_alignment(text_alignment_(variables))
.set_foreground_color(color_(variables))
.set_foreground_color(fg_color)
.set_maximum_width(maximum_width_(variables))
.set_maximum_height(maximum_height_(variables), true)
.set_ellipse_mode(variables.has_key("text_wrap_mode")
@ -1296,6 +1305,9 @@ void text_shape::draw(
// Get the resulting texture.
texture& txt = text_renderer.render_and_get_texture();
// Set texture alpha.
set_texture_alpha(txt, saved_alpha);
// TODO: should use pango_text::get_size but the dimensions are inaccurate. Investigate.
texture::info info = txt.get_info();