Optimize drawing horizontal/vertical lines

On DC with a non-rotated coordinate system drawing a filled rectangle with ExtTextOut() Win API is faster than drawing a line with MoveTo()/LineTo() so on such DCs we can use ExtTextOut() to draw horizontal/vertical lines with solid colors and square ends instead of calling MoveTo()/LineTo().

See #18517.

include/wx/msw/private.h

@@ -1109,6 +1109,8 @@ extern WXDLLIMPEXP_CORE wxSize wxGetHiconSize(HICON hicon);
 
 WXDLLIMPEXP_CORE void wxDrawLine(HDC hdc, int x1, int y1, int x2, int y2);
 
+WXDLLIMPEXP_CORE void wxDrawHVLine(HDC hdc, int x1, int y1, int x2, int y2, COLORREF color, int width);
+
 // fill the client rect of the given window on the provided dc using this brush
 inline void wxFillRect(HWND hwnd, HDC hdc, HBRUSH hbr)
 {

src/msw/dc.cpp

@@ -819,7 +819,31 @@ void wxMSWDCImpl::DoCrossHair(wxCoord x, wxCoord y)
 
 void wxMSWDCImpl::DoDrawLine(wxCoord x1, wxCoord y1, wxCoord x2, wxCoord y2)
 {
-    wxDrawLine(GetHdc(), XLOG2DEV(x1), YLOG2DEV(y1), XLOG2DEV(x2), YLOG2DEV(y2));
+    // We have optimized function to draw physical vertical or horizontal lines
+    // with solid color and square ends.
+    // Because checking wheteher the line would be horizontal/vertical
+    // in the device coordinate system is complex so we only check whether
+    // the line is horizontal/vertical in the logical coordinates and use
+    // optimized function only for DC which coordinate system is for sure
+    // not rotated (graphics mode of the DC != GM_ADVANCED).
+    // Moreover, optimized function can be used only for regular lines with pen
+    // width > 0 because it doesn't support drawing non-scaled 1-pixel wide
+    // lines when pen width is 0.
+    if ( (x1 == x2 || y1 == y2) &&
+         ::GetGraphicsMode(GetHdc()) != GM_ADVANCED && // ensure DC is not rotated
+         m_pen.IsNonTransparent() && // this calls IsOk() too
+         m_pen.GetStyle() == wxPENSTYLE_SOLID &&
+         m_pen.GetWidth() > 0 &&
+         (m_pen.GetWidth() == 1 || m_pen.GetCap() == wxCAP_BUTT)
+       )
+    {
+        wxDrawHVLine(GetHdc(), XLOG2DEV(x1), YLOG2DEV(y1), XLOG2DEV(x2), YLOG2DEV(y2),
+                     wxColourToRGB(m_pen.GetColour()), m_pen.GetWidth());
+    }
+    else
+    {
+        wxDrawLine(GetHdc(), XLOG2DEV(x1), YLOG2DEV(y1), XLOG2DEV(x2), YLOG2DEV(y2));
+    }
 
     CalcBoundingBox(x1, y1);
     CalcBoundingBox(x2, y2);

src/msw/utilsgui.cpp

@@ -209,6 +209,35 @@ void wxDrawLine(HDC hdc, int x1, int y1, int x2, int y2)
     MoveToEx(hdc, x1, y1, NULL); LineTo((HDC) hdc, x2, y2);
 }
 
+// Function dedicated to drawing horizontal/vertical lines with solid color
+// It fills rectangle representing the line with ::ExtTextOut() API which
+// apparently is faster than ::MoveTo()/::LineTo() on DC with a non-rotated
+// coordinate system.
+void wxDrawHVLine(HDC hdc, int x1, int y1, int x2, int y2, COLORREF color, int width)
+{
+    wxASSERT(x1 == x2 || y1 == y2);
+
+    int w1 = width / 2;
+    int w2 = width - w1;
+    RECT r;
+    if ( y1 == y2 )
+    {
+        if ( x1 == x2 )
+            return;
+        ::SetRect(&r, x1, y1 - w1, x2, y1 + w2);
+    }
+    else
+    {
+        ::SetRect(&r, x1 - w1, y1, x2 + w2, y2);
+    }
+
+    COLORREF bgColorOrig = ::GetBkColor(hdc);
+    ::SetBkColor(hdc, color);
+
+    ::ExtTextOutW(hdc, 0, 0, ETO_OPAQUE, &r, L"", 0, NULL);
+
+    ::SetBkColor(hdc, bgColorOrig);
+}
 
 // ----------------------------------------------------------------------------
 // Shell API wrappers