tdf#130991 Fit the drop-down arrow into its rect

Looking at the original fixed-size arrow painting code replaced
in commit b62c43d1200e524369d9c7c2bd1dad3044efd672 ("Anti-alias
toolbar button drop-downs."), it  used some fixed values of 5
and 3 to match the arrow box width of 11.

The new code assumes the width is the expected arrow size, minus
a minimal margin to separate the arrow from the button border,
and there is enough height available. Based on these assumptions,
the code now scales, positions and paints the triangle to fill
the available space.

Change-Id: Ied721e494d105106086ef6252e72ae7395eafe08
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/97537
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

1 files changed, 16 insertions, 15 deletions

diff --git a/vcl/source/window/toolbox.cxx b/vcl/source/window/toolbox.cxx
index 02600732c747..935a7e3ae9ec 100644
--- a/vcl/source/window/toolbox.cxx
+++ b/vcl/source/window/toolbox.cxx
@@ -2391,27 +2391,28 @@ static void ImplDrawDropdownArrow(vcl::RenderContext& rRenderContext, const tool
             rRenderContext.SetFillColor(COL_BLACK);
     }
 
-    float fScaleFactor = rRenderContext.GetDPIScaleFactor();
-
     tools::Polygon aPoly(4);
 
-    long width = round(rDropDownRect.getHeight()/5.5) * fScaleFactor; // scale triangle depending on theme/toolbar height with 7 for gtk, 5 for gen
-    long height = round(rDropDownRect.getHeight()/9.5) * fScaleFactor; // 4 for gtk, 3 for gen
-    if (width < 4) width = 4;
-    if (height < 3) height = 3;
+    // the assumption is, that the width always specifies the size of the expected arrow.
+    const long nMargin = round(2 * rRenderContext.GetDPIScaleFactor());
+    const long nSize = rDropDownRect.getWidth() - 2 * nMargin;
+    const long nHalfSize = (nSize + 1) / 2;
+    const long x = rDropDownRect.Left() + nMargin + (bRotate ? (rDropDownRect.getWidth() - nHalfSize) / 2 : 0);
+    const long y = rDropDownRect.Top() + nMargin + (rDropDownRect.getHeight() - (bRotate ? nSize : nHalfSize)) / 2;
 
-    long x = rDropDownRect.Left() + (rDropDownRect.getWidth() - width)/2;
-    long y = rDropDownRect.Top() + (rDropDownRect.getHeight() - height)/2;
-
-    long halfwidth = (width+1)>>1;
     aPoly.SetPoint(Point(x, y), 0);
-    aPoly.SetPoint(Point(x + halfwidth, y + height), 1);
-    aPoly.SetPoint(Point(x + halfwidth*2, y), 2);
+    if (bRotate) // >
+    {
+        aPoly.SetPoint(Point(x, y + nSize), 1);
+        aPoly.SetPoint(Point(x + nHalfSize, y + nHalfSize), 2);
+    }
+    else // v
+    {
+        aPoly.SetPoint(Point(x + nHalfSize, y + nHalfSize), 1);
+        aPoly.SetPoint(Point(x + nSize, y), 2);
+    }
     aPoly.SetPoint(Point(x, y), 3);
 
-    if (bRotate) // TESTME: harder ...
-        aPoly.Rotate(Point(x,y+height/2),2700);
-
     auto aaflags = rRenderContext.GetAntialiasing();
     rRenderContext.SetAntialiasing(AntialiasingFlags::EnableB2dDraw);
     rRenderContext.DrawPolygon( aPoly );