Implemented the H slider.

windows/colordialog.cpp

@@ -1,6 +1,8 @@
 // 16 may 2016
 #include "uipriv_windows.hpp"
 
+// TODO should the d2dscratch programs capture mouse?
+
 struct colorDialog {
 	HWND hwnd;
 
@@ -282,7 +284,7 @@ static void updateDialog(struct colorDialog *c, HWND whichChanged)
 
 	// TODO TRUE?
 	invalidateRect(c->svChooser, NULL, TRUE);
-//TODO	invalidateRect(c->hSlider, NULL, TRUE);
+	invalidateRect(c->hSlider, NULL, TRUE);
 //TODO	invalidateRect(c->preview, NULL, TRUE);
 //TODO	invalidateRect(c->opacitySlider, NULL, TRUE);
 
@@ -449,7 +451,7 @@ static void drawSVChooser(struct colorDialog *c, ID2D1RenderTarget *rt)
 	bprop.opacity = 1.0;		// the marker should always be opaque
 	hr = rt->CreateSolidColorBrush(&mcolor, &bprop, &markerBrush);
 	if (hr != S_OK)
-		logHRESULT(L"error creating brush for SV chooser", hr);
+		logHRESULT(L"error creating brush for SV chooser marker", hr);
 	rt->DrawEllipse(&mparam, markerBrush, 2, NULL);
 	markerBrush->Release();
 }
@@ -482,6 +484,136 @@ static LRESULT CALLBACK svChooserSubProc(HWND hwnd, UINT uMsg, WPARAM wParam, LP
 	return DefSubclassProc(hwnd, uMsg, wParam, lParam);
 }
 
+// the gradient stuff also comes from http://blogs.msdn.com/b/wpfsdk/archive/2006/10/26/uncommon-dialogs--font-chooser-and-color-picker-dialogs.aspx
+#define nStops (30)
+#define degPerStop (360 / nStops)
+#define stopIncr (1.0 / ((double) nStops))
+
+static void drawHSlider(struct colorDialog *c, ID2D1RenderTarget *rt)
+{
+	D2D1_SIZE_F size;
+	D2D1_RECT_F rect;
+	D2D1_GRADIENT_STOP stops[nStops];
+	double r, g, b;
+	int i;
+	double h;
+	ID2D1GradientStopCollection *collection;
+	D2D1_LINEAR_GRADIENT_BRUSH_PROPERTIES lprop;
+	D2D1_BRUSH_PROPERTIES bprop;
+	ID2D1LinearGradientBrush *brush;
+	double hypot, leg;
+	D2D1_POINT_2F center;
+	D2D1_MATRIX_3X2_F oldtf, rotate;
+	D2D1_COLOR_F mcolor;
+	ID2D1SolidColorBrush *markerBrush;
+	HRESULT hr;
+
+	size = rt->GetSize();
+	rect.left = size.width / 6;		// leftmost sixth for arrow
+	rect.top = 0;
+	rect.right = size.width;
+	rect.bottom = size.height;
+
+	for (i = 0; i < nStops; i++) {
+		h = ((double) (i * degPerStop)) / 360.0;
+		if (i == (nStops - 1))
+			h = 0;
+		hsv2RGB(h, 1.0, 1.0, &r, &g, &b);
+		stops[i].position = ((double) i) * stopIncr;
+		stops[i].color.r = r;
+		stops[i].color.g = g;
+		stops[i].color.b = b;
+		stops[i].color.a = 1.0;
+	}
+	// and pin the last one
+	stops[i - 1].position = 1.0;
+
+	hr = rt->CreateGradientStopCollection(stops, nStops,
+		// note that in this case this gamma is explicitly specified by the original
+		D2D1_GAMMA_2_2, D2D1_EXTEND_MODE_CLAMP,
+		&collection);
+	if (hr != S_OK)
+		logHRESULT(L"error creating stop collection for H slider gradient", hr);
+	ZeroMemory(&lprop, sizeof (D2D1_LINEAR_GRADIENT_BRUSH_PROPERTIES));
+	lprop.startPoint.x = (rect.right - rect.left) / 2;
+	lprop.startPoint.y = 0;
+	lprop.endPoint.x = (rect.right - rect.left) / 2;
+	lprop.endPoint.y = size.height;
+	ZeroMemory(&bprop, sizeof (D2D1_BRUSH_PROPERTIES));
+	bprop.opacity = 1.0;
+	bprop.transform._11 = 1;
+	bprop.transform._22 = 1;
+	hr = rt->CreateLinearGradientBrush(&lprop, &bprop,
+		collection, &brush);
+	if (hr != S_OK)
+		logHRESULT(L"error creating gradient brush for H slider", hr);
+	rt->FillRectangle(&rect, brush);
+	brush->Release();
+	collection->Release();
+
+	// now draw a black arrow
+	// to avoid needing a geometry, this will just be a rotated square
+	center.x = 0;
+	center.y = c->h * size.height;
+	// compute the length of each side; the diagonal of the square is 2 * offset to gradient
+	hypot = rect.left;
+	// a^2 + a^2 = c^2 -> 2a^2 = c^2
+	// a = sqrt(c^2/2)
+	hypot *= hypot;
+	hypot /= 2;
+	leg = sqrt(hypot);
+	rect.left = -leg;
+	rect.top = center.y - leg;
+	rect.right = leg;
+	rect.bottom = center.y + leg;
+
+	// now we need to rotate the render target 45° (either way works) about the center point
+	rt->GetTransform(&oldtf);
+	rotate = oldtf * D2D1::Matrix3x2F::Rotation(45, center);
+	rt->SetTransform(&rotate);
+
+	// and draw
+	mcolor.r = 0.0;
+	mcolor.g = 0.0;
+	mcolor.b = 0.0;
+	mcolor.a = 1.0;
+	hr = rt->CreateSolidColorBrush(&mcolor, &bprop, &markerBrush);
+	if (hr != S_OK)
+		logHRESULT(L"error creating brush for H slider marker", hr);
+	rt->FillRectangle(&rect, markerBrush);
+	markerBrush->Release();
+
+	// clean up
+	rt->SetTransform(&oldtf);
+}
+
+static LRESULT CALLBACK hSliderSubProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
+{
+	ID2D1RenderTarget *rt;
+	struct colorDialog *c;
+	D2D1_POINT_2F *pos;
+	D2D1_SIZE_F *size;
+
+	c = (struct colorDialog *) dwRefData;
+	switch (uMsg) {
+	case msgD2DScratchPaint:
+		rt = (ID2D1RenderTarget *) lParam;
+		drawHSlider(c, rt);
+		return 0;
+	case msgD2DScratchLButtonDown:
+		pos = (D2D1_POINT_2F *) wParam;
+		size = (D2D1_SIZE_F *) lParam;
+		c->h = pos->y / size->height;
+		updateDialog(c, NULL);
+		return 0;
+	case WM_NCDESTROY:
+		if (RemoveWindowSubclass(hwnd, hSliderSubProc, uIdSubclass) == FALSE)
+			logLastError(L"error removing color dialog H slider subclass");
+		break;
+	}
+	return DefSubclassProc(hwnd, uMsg, wParam, lParam);
+}
+
 // TODO extract into d2dscratch.cpp, use in font dialog
 HWND replaceWithD2DScratch(HWND parent, int id, SUBCLASSPROC subproc, void *data)
 {
@@ -608,6 +740,7 @@ static struct colorDialog *beginColorDialog(HWND hwnd, LPARAM lParam)
 	c->editHex = getDlgItem(c->hwnd, rcHex);
 
 	c->svChooser = replaceWithD2DScratch(c->hwnd, rcColorSVChooser, svChooserSubProc, c);
+	c->hSlider = replaceWithD2DScratch(c->hwnd, rcColorHSlider, hSliderSubProc, c);
 
 	fixupControlPositions(c);