From 4b1ab4db9705248f9242d5b1260a22740c1b72f4 Mon Sep 17 00:00:00 2001
From: Martin Fouilleul <martinfouilleul@gmail.com>
Date: Wed, 23 Aug 2023 12:35:25 +0200
Subject: [PATCH] expose oc_surface_contents_scaling() to get dpi scaling from
 a surface

---
 samples/fluid/src/main.c        | 28 +++++++++++++++-------------
 samples/glesTriangle/src/main.c |  4 +++-
 src/wasmbind/surface_api.json   |  8 ++++++++
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/samples/fluid/src/main.c b/samples/fluid/src/main.c
index 82a9d4a..348b600 100644
--- a/samples/fluid/src/main.c
+++ b/samples/fluid/src/main.c
@@ -140,6 +140,8 @@ frame_buffer divBuffer[4];
 
 GLuint vertexBuffer;
 
+oc_surface surface;
+
 //----------------------------------------------------------------
 //NOTE(martin): initialization
 //----------------------------------------------------------------
@@ -419,10 +421,10 @@ ORCA_EXPORT void oc_on_mouse_up(int button)
 
 ORCA_EXPORT void oc_on_mouse_move(float x, float y, float dx, float dy)
 {
-    mouseInput.x = x * 2;
-    mouseInput.y = y * 2;
-    mouseInput.deltaX = dx * 2;
-    mouseInput.deltaY = dy * 2;
+    mouseInput.x = x;
+    mouseInput.y = y;
+    mouseInput.deltaX = dx;
+    mouseInput.deltaY = dy;
 }
 
 void init_color_checker()
@@ -580,19 +582,20 @@ void input_splat(float t)
     //NOTE: apply force and dye
     if(mouseInput.down && (mouseInput.deltaX || mouseInput.deltaY))
     {
+	    oc_vec2 scaling = oc_surface_contents_scaling(surface);
         // account for margin
         float margin = 32;
 
         float offset = margin / texWidth;
         float ratio = 1 - 2 * margin / texWidth;
 
-        float splatPosX = (mouseInput.x / frameWidth) * ratio + offset;
-        float splatPosY = (1 - mouseInput.y / frameHeight) * ratio + offset;
+        float splatPosX = (mouseInput.x * scaling.x / frameWidth) * ratio + offset;
+        float splatPosY = (1 - mouseInput.y * scaling.y / frameHeight) * ratio + offset;
 
-        float splatVelX = (10000. * DELTA * mouseInput.deltaX / frameWidth) * ratio;
-        float splatVelY = (-10000. * DELTA * mouseInput.deltaY / frameWidth) * ratio;
+        float splatVelX = (10000. * DELTA * mouseInput.deltaX * scaling.x / frameWidth) * ratio;
+        float splatVelY = (-10000. * DELTA * mouseInput.deltaY * scaling.y / frameWidth) * ratio;
 
-        float intensity = 100 * sqrtf(square(ratio * mouseInput.deltaX / frameWidth) + square(ratio * mouseInput.deltaY / frameHeight));
+        float intensity = 100 * sqrtf(square(ratio * mouseInput.deltaX * scaling.x / frameWidth) + square(ratio * mouseInput.deltaY * scaling.y / frameHeight));
 
         float r = intensity * (sinf(2 * M_PI * 0.1 * t) + 1);
         float g = 0.5 * intensity * (cosf(2 * M_PI * 0.1 / M_E * t + 654) + 1);
@@ -609,8 +612,6 @@ void input_splat(float t)
 
 float testDiv[texWidth / 2][texWidth / 2][4];
 
-oc_surface surface;
-
 ORCA_EXPORT void oc_on_init()
 {
     oc_log_info("Hello, world (from C)");
@@ -682,8 +683,9 @@ ORCA_EXPORT void oc_on_init()
 
 ORCA_EXPORT void oc_on_resize(u32 width, u32 height)
 {
-    frameWidth = width * 2;
-    frameHeight = height * 2;
+    oc_vec2 scaling = oc_surface_contents_scaling(surface);
+    frameWidth = width * scaling.x;
+    frameHeight = height * scaling.y;
 }
 
 ORCA_EXPORT void oc_on_frame_refresh()
diff --git a/samples/glesTriangle/src/main.c b/samples/glesTriangle/src/main.c
index 4517302..9ccb81a 100644
--- a/samples/glesTriangle/src/main.c
+++ b/samples/glesTriangle/src/main.c
@@ -96,7 +96,9 @@ ORCA_EXPORT void oc_on_frame_refresh(void)
 
     static float alpha = 0;
 
-    glViewport(0, 0, frameSize.x * 2, frameSize.y * 2);
+    oc_vec2 scaling = oc_surface_contents_scaling(surface);
+
+    glViewport(0, 0, frameSize.x * scaling.x, frameSize.y * scaling.y);
 
     GLfloat matrix[] = { cosf(alpha) / aspect, sinf(alpha), 0, 0,
                          -sinf(alpha) / aspect, cosf(alpha), 0, 0,
diff --git a/src/wasmbind/surface_api.json b/src/wasmbind/surface_api.json
index 942f8bd..3166c0d 100644
--- a/src/wasmbind/surface_api.json
+++ b/src/wasmbind/surface_api.json
@@ -52,6 +52,14 @@
 		{"name": "surface",
 		 "type": {"name": "oc_surface", "tag": "S"}}]
 },
+{
+    "name": "oc_surface_contents_scaling",
+    "cname": "oc_surface_contents_scaling",
+    "ret": {"name": "oc_vec2", "tag": "S"},
+    "args": [
+        {"name": "surface",
+         "type": {"name": "oc_surface", "tag": "S"}}]
+},
 {
 	"name": "oc_surface_render_commands",
 	"cname": "orca_surface_render_commands",
-- 
2.25.1