From 00ef2703e211cab8efea365b2690c7118cbbe661 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ole-Andr=C3=A9=20Rodlie?= <ole.andre.rodlie@gmail.com>
Date: Tue, 11 Jun 2024 21:12:52 +0200
Subject: [PATCH] Update CairoHelper

* https://github.com/NatronGitHub/openfx-arena/issues/25
* https://github.com/NatronGitHub/Natron/issues/970
---
 Helpers/CairoHelper.cpp | 68 +++++++++++++++++++++++++++++++++++------
 Helpers/CairoHelper.h   | 36 ++++++++++++++++++----
 2 files changed, 88 insertions(+), 16 deletions(-)

diff --git a/Helpers/CairoHelper.cpp b/Helpers/CairoHelper.cpp
index 5f382f8..69b0bfc 100644
--- a/Helpers/CairoHelper.cpp
+++ b/Helpers/CairoHelper.cpp
@@ -20,22 +20,70 @@
 
 #include <cmath>
 
-void CairoHelper::applyRotate(cairo_t *cr,
-                              double rotate,
-                              XY origin)
+void
+CairoHelper::applyFlip(cairo_t *cr,
+                       const int &height)
 {
-    if (!cr || rotate == 0.) { return; }
+    if (!cr || height < 1) { return; }
+    cairo_scale(cr, 1.0f, -1.0f);
+    cairo_translate(cr, 0.0f, -height);
+}
+
+void
+CairoHelper::applyPosition(cairo_t *cr,
+                           const _XY &position)
+{
+    if (!cr) { return; }
+    cairo_move_to(cr, position.x, position.y);
+}
+
+void
+CairoHelper::applyScale(cairo_t *cr,
+                        const _XY &scale)
+{
+    if (!cr || (scale.x == 0. && scale.y == 0.)) { return; }
+    cairo_scale(cr, scale.x, scale.y);
+}
 
+void
+CairoHelper::applySkew(cairo_t *cr,
+                       const _XY &skew,
+                       const _XY &origin)
+{
+    if (!cr || (skew.x == 0. && skew.y == 0.)) { return; }
+    double x = skew.x;
+    double y = skew.y;
+    if (x != 0.) { x = -x; }
+    if (y != 0.) { y = -y; }
+    cairo_matrix_t matrix = {
+        1.0,  y,
+        x , 1.0,
+        0.0, 0.0
+    };
     cairo_translate(cr, origin.x, origin.y);
-    cairo_rotate(cr, -rotate * (M_PI / 180.0));
+    cairo_transform(cr, &matrix);
     cairo_translate(cr, -origin.x, -origin.y);
 }
 
-void CairoHelper::applyFlip(cairo_t *cr,
-                            int height)
+void
+CairoHelper::applyRotate(cairo_t *cr,
+                         const double &rotate,
+                         const _XY &origin)
 {
-    if (!cr || height < 1) { return; }
+    if (!cr || rotate == 0.) { return; }
+    cairo_translate(cr, origin.x, origin.y);
+    cairo_rotate(cr, -rotate * (M_PI / 180.0));
+    cairo_translate(cr, -origin.x, -origin.y);
+}
 
-    cairo_scale(cr, 1.0f, -1.0f);
-    cairo_translate(cr, 0.0f, -height);
+void
+CairoHelper::applyTransform(cairo_t *cr,
+                            const _Transform &transform)
+{
+    if (!cr) { return; }
+    if (transform.flip) { applyFlip(cr, transform.height); }
+    if (transform.position) { applyPosition(cr, transform.origin); }
+    applyScale(cr, transform.scale);
+    applySkew(cr, transform.skew, transform.origin);
+    applyRotate(cr, transform.rotate, transform.origin);
 }
diff --git a/Helpers/CairoHelper.h b/Helpers/CairoHelper.h
index 1bf47bd..9f3e7e7 100644
--- a/Helpers/CairoHelper.h
+++ b/Helpers/CairoHelper.h
@@ -24,18 +24,42 @@
 class CairoHelper
 {
 public:
-    struct XY
+    struct _XY
     {
         double x;
         double y;
     };
-    /** @brief apply rotate */
-    static void applyRotate(cairo_t *cr,
-                            double rotate,
-                            XY origin);
+    struct _Transform
+    {
+        _XY origin;
+        _XY scale;
+        _XY skew;
+        int width;
+        int height;
+        double rotate;
+        bool position;
+        bool flip;
+    };
     /** @brief apply flip */
     static void applyFlip(cairo_t *cr,
-                          int height);
+                          const int &height);
+    /** @brief apply position */
+    static void applyPosition(cairo_t *cr,
+                              const _XY &position);
+    /** @brief apply scale */
+    static void applyScale(cairo_t *cr,
+                           const _XY &scale);
+    /** @brief apply skew */
+    static void applySkew(cairo_t *cr,
+                          const _XY &skew,
+                          const _XY &origin);
+    /** @brief apply rotate */
+    static void applyRotate(cairo_t *cr,
+                            const double &rotate,
+                            const _XY &origin);
+    /** @brief apply transform */
+    static void applyTransform(cairo_t *cr,
+                               const _Transform &transform);
 };
 
 #endif // CAIROHELPER_H