From 41910bd5cd509346f74cd3b0ffb21bc8c4b40bfd Mon Sep 17 00:00:00 2001
From: tim_rawlinson <rawlinson@users.noreply.github.com>
Date: Sat, 23 Feb 2019 14:03:20 +0000
Subject: [PATCH] Make background color affect checkerboard

---
 src/desktop.cpp             |  2 +-
 src/display/cairo-utils.cpp | 17 ++++++++++++++---
 src/display/cairo-utils.h   |  2 +-
 src/display/sp-canvas.cpp   |  5 +++--
 src/display/sp-canvas.h     |  2 +-
 5 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/desktop.cpp b/src/desktop.cpp
index ea6ef1bc3e..3f40e7e75d 100644
--- a/src/desktop.cpp
+++ b/src/desktop.cpp
@@ -1874,7 +1874,7 @@ static void _namedview_modified (SPObject *obj, guint flags, SPDesktop *desktop)
 
     if (flags & SP_OBJECT_MODIFIED_FLAG) {
         if (nv->pagecheckerboard) {
-            desktop->canvas->setBackgroundCheckerboard();
+            desktop->canvas->setBackgroundCheckerboard(nv->pagecolor);
         } else {
             desktop->canvas->setBackgroundColor(nv->pagecolor);
         }
diff --git a/src/display/cairo-utils.cpp b/src/display/cairo-utils.cpp
index 6dd343298e..0a1dbd3d66 100644
--- a/src/display/cairo-utils.cpp
+++ b/src/display/cairo-utils.cpp
@@ -1280,18 +1280,29 @@ int ink_cairo_surface_linear_to_srgb(cairo_surface_t *surface)
 }
 
 cairo_pattern_t *
-ink_cairo_pattern_create_checkerboard()
+ink_cairo_pattern_create_checkerboard(guint32 rgba)
 {
     int const w = 6;
     int const h = 6;
 
+    double r = SP_RGBA32_R_F(rgba);
+    double g = SP_RGBA32_G_F(rgba);
+    double b = SP_RGBA32_B_F(rgba);
+
+    float hsl[3];
+    SPColor::rgb_to_hsl_floatv(hsl, r, g, b);    
+    hsl[2] += hsl[2] < 0.08 ? 0.08 : -0.08; // 0.08 = 0.77-0.69, the original checkerboard colors.
+
+    float rgb2[3];
+    SPColor::hsl_to_rgb_floatv(rgb2, hsl[0], hsl[1], hsl[2]);
+
     cairo_surface_t *s = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 2*w, 2*h);
 
     cairo_t *ct = cairo_create(s);
     cairo_set_operator(ct, CAIRO_OPERATOR_SOURCE);
-    cairo_set_source_rgb(ct, 0.77, 0.77, 0.77);
+    cairo_set_source_rgb(ct, r, g, b);
     cairo_paint(ct);
-    cairo_set_source_rgb(ct, 0.69, 0.69, 0.69);
+    cairo_set_source_rgb(ct, rgb2[0], rgb2[1], rgb2[2]);
     cairo_rectangle(ct, 0, 0, w, h);
     cairo_rectangle(ct, w, h, w, h);
     cairo_fill(ct);
diff --git a/src/display/cairo-utils.h b/src/display/cairo-utils.h
index 61f2365939..fbcee5413a 100644
--- a/src/display/cairo-utils.h
+++ b/src/display/cairo-utils.h
@@ -173,7 +173,7 @@ double srgb_to_linear( const double c );
 int ink_cairo_surface_srgb_to_linear(cairo_surface_t *surface);
 int ink_cairo_surface_linear_to_srgb(cairo_surface_t *surface);
 
-cairo_pattern_t *ink_cairo_pattern_create_checkerboard();
+cairo_pattern_t *ink_cairo_pattern_create_checkerboard(guint32 rgba = 0xC4C4C4FF);
 
 GdkPixbuf *ink_pixbuf_create_from_cairo_surface(cairo_surface_t *s);
 void convert_pixels_pixbuf_to_argb32(guchar *data, int w, int h, int rs);
diff --git a/src/display/sp-canvas.cpp b/src/display/sp-canvas.cpp
index 8d10ccb33d..8e3851dd73 100644
--- a/src/display/sp-canvas.cpp
+++ b/src/display/sp-canvas.cpp
@@ -2728,12 +2728,13 @@ void SPCanvas::setBackgroundColor(guint32 rgba) {
     addIdle();
 }
 
-void SPCanvas::setBackgroundCheckerboard() {
+void SPCanvas::setBackgroundCheckerboard(guint32 rgba)
+{
     if (_background_is_checkerboard) return;
     if (_background) {
         cairo_pattern_destroy(_background);
     }
-    _background = ink_cairo_pattern_create_checkerboard();
+    _background = ink_cairo_pattern_create_checkerboard(rgba);
     _background_is_checkerboard = true;
     dirtyAll();
     addIdle();
diff --git a/src/display/sp-canvas.h b/src/display/sp-canvas.h
index 368a058384..9b782e8a47 100644
--- a/src/display/sp-canvas.h
+++ b/src/display/sp-canvas.h
@@ -91,7 +91,7 @@ struct SPCanvas {
     SPCanvasGroup *getRoot();
 
     void setBackgroundColor(guint32 rgba);
-    void setBackgroundCheckerboard();
+    void setBackgroundCheckerboard(guint32 rgba = 0xC4C4C4FF);
 
     /// Returns new canvas as widget.
     static GtkWidget *createAA();
-- 
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