From 00274c57a936e46110cb6407b23a2d32896c39fe Mon Sep 17 00:00:00 2001
From: patrick96 <p.ziegler96@gmail.com>
Date: Fri, 22 Nov 2019 03:11:12 +0100
Subject: [PATCH] fix(renderer): Falloff gradient

Before it did not take into account borders or a tray on the left.
It also sometimes rendered the gradient way to large
---
 include/cairo/context.hpp   |  6 +++---
 src/components/renderer.cpp | 37 ++++++++++++++++++++++++++-----------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/include/cairo/context.hpp b/include/cairo/context.hpp
index 8ed4f500..f6ab233e 100644
--- a/include/cairo/context.hpp
+++ b/include/cairo/context.hpp
@@ -108,10 +108,9 @@ namespace cairo {
     }
 
     context& operator<<(const linear_gradient& l) {
-      if (l.steps.size() >= 2) {
+      auto stops = l.steps.size();
+      if (stops >= 2) {
         auto pattern = cairo_pattern_create_linear(l.x1, l.y1, l.x2, l.y2);
-        *this << pattern;
-        auto stops = l.steps.size();
         auto step = 1.0 / (stops - 1);
         auto offset = 0.0;
         for (auto&& color : l.steps) {
@@ -124,6 +123,7 @@ namespace cairo {
           // clang-format on
           offset += step;
         }
+        *this << pattern;
         cairo_pattern_destroy(pattern);
       }
       return *this;
diff --git a/src/components/renderer.cpp b/src/components/renderer.cpp
index 81d08b03..599f8589 100644
--- a/src/components/renderer.cpp
+++ b/src/components/renderer.cpp
@@ -341,7 +341,7 @@ void renderer::flush(alignment a) {
   double w = static_cast<int>(block_w(a) + 0.5);
   double h = static_cast<int>(block_h(a) + 0.5);
   double xw = x + w;
-  bool fits{xw <= m_rect.x + m_rect.width};
+  bool fits{xw <= m_rect.width};
 
   m_log.trace("renderer: flush(%i geom=%gx%g+%g+%g, falloff=%i)", static_cast<int>(a), w, h, x, y, !fits);
 
@@ -359,19 +359,34 @@ void renderer::flush(alignment a) {
   *m_context << m_blocks[a].pattern;
   m_context->paint();
 
-  if (!fits) {
-    // Paint falloff gradient at the end of the visible block
-    // to indicate that the content expands past the canvas
-    double fx = w - (xw - m_rect.width);
-    double fsize = std::max(5.0, std::min(std::abs(fx), 30.0));
-    m_log.trace("renderer: Drawing falloff (pos=%g, size=%g)", fx, fsize);
-    *m_context << cairo::linear_gradient{fx - fsize, 0.0, fx, 0.0, {0x00000000, 0xFF000000}};
-    m_context->paint(0.25);
-  }
-
   *m_context << cairo::abspos{0.0, 0.0};
   m_context->destroy(&m_blocks[a].pattern);
   m_context->restore();
+
+  if (!fits) {
+    // Paint falloff gradient at the end of the visible block
+    // to indicate that the content expands past the canvas
+
+    /*
+     * How many pixels are hidden
+     */
+    double overflow = xw - m_rect.width;
+    double visible_width = w - overflow;
+
+    /*
+     * Width of the falloff gradient. Depends on how much of the block is hidden
+     */
+    double fsize = std::max(5.0, std::min(std::abs(overflow), 30.0));
+    m_log.trace("renderer: Drawing falloff (pos=%g, size=%g, overflow=%g)", visible_width - fsize, fsize, overflow);
+    m_context->save();
+    *m_context << cairo::translate{(double) m_rect.x, (double) m_rect.y};
+    *m_context << cairo::abspos{0.0, 0.0};
+    *m_context << cairo::rect{x + visible_width - fsize, y, fsize, h};
+    m_context->clip(true);
+    *m_context << cairo::linear_gradient{x + visible_width - fsize, y, x + visible_width, y, {0x00000000, 0xFF000000}};
+    m_context->paint(0.25);
+    m_context->restore();
+  }
 }
 
 /**