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Link graph GUI: Fix poor contrast in graph legend window cargo labels.

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Select foreground colour depending on brightness of background.
This commit is contained in:
Jonathan G Rennison
2016-11-21 23:08:13 +00:00
parent 55057110a5
commit fa261207ae
3 changed files with 5 additions and 5 deletions
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6
src/gfx.cpp
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@@ -1113,14 +1113,14 @@ void DoPaletteAnimations()
* @param background Background colour. * @param background Background colour.
* @return TC_BLACK or TC_WHITE depending on what gives a better contrast. * @return TC_BLACK or TC_WHITE depending on what gives a better contrast.
*/ */
TextColour GetContrastColour(uint8 background) TextColour GetContrastColour(uint8 background, uint8 threshold)
{ {
Colour c = _cur_palette.palette[background]; Colour c = _cur_palette.palette[background];
/* Compute brightness according to http://www.w3.org/TR/AERT#color-contrast. /* Compute brightness according to http://www.w3.org/TR/AERT#color-contrast.
* The following formula computes 1000 * brightness^2, with brightness being in range 0 to 255. */ * The following formula computes 1000 * brightness^2, with brightness being in range 0 to 255. */
uint sq1000_brightness = c.r * c.r * 299 + c.g * c.g * 587 + c.b * c.b * 114; uint sq1000_brightness = c.r * c.r * 299 + c.g * c.g * 587 + c.b * c.b * 114;
/* Compare with threshold brightness 128 (50%) */ /* Compare with threshold brightness which defaults to 128 (50%) */
return sq1000_brightness < 128 * 128 * 1000 ? TC_WHITE : TC_BLACK; return sq1000_brightness < threshold * 128 * 1000 ? TC_WHITE : TC_BLACK;
} }
/** /**

2
src/gfx_func.h
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@@ -185,7 +185,7 @@ inline int GetCharacterHeight(FontSize size)
extern DrawPixelInfo *_cur_dpi; extern DrawPixelInfo *_cur_dpi;
TextColour GetContrastColour(uint8 background); TextColour GetContrastColour(uint8 background, uint8 threshold = 128);
/** /**
* All 16 colour gradients * All 16 colour gradients

2
src/linkgraph/linkgraph_gui.cpp
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@@ -496,7 +496,7 @@ void LinkGraphLegendWindow::DrawWidget(const Rect &r, int widget) const
if (this->IsWidgetDisabled(widget)) return; if (this->IsWidgetDisabled(widget)) return;
CargoSpec *cargo = CargoSpec::Get(widget - WID_LGL_CARGO_FIRST); CargoSpec *cargo = CargoSpec::Get(widget - WID_LGL_CARGO_FIRST);
GfxFillRect(r.left + 2, r.top + 2, r.right - 2, r.bottom - 2, cargo->legend_colour); GfxFillRect(r.left + 2, r.top + 2, r.right - 2, r.bottom - 2, cargo->legend_colour);
DrawString(r.left, r.right, (r.top + r.bottom + 1 - FONT_HEIGHT_SMALL) / 2, cargo->abbrev, TC_BLACK, SA_HOR_CENTER); DrawString(r.left, r.right, (r.top + r.bottom + 1 - FONT_HEIGHT_SMALL) / 2, cargo->abbrev, GetContrastColour(cargo->legend_colour, 42), SA_HOR_CENTER);
} }
} }