From 858a1f2c1a86bed59779a0c34db709e9f557c743 Mon Sep 17 00:00:00 2001
From: Froxwin <56168224+Froxwin@users.noreply.github.com>
Date: Tue, 10 Mar 2026 16:27:52 +0000
Subject: [PATCH] feat: add canvas zoom

---
 src/application/applicationstate.c |  3 +++
 src/core/matrix.c                  | 22 +++++++++++++++
 src/core/matrix.h                  |  2 ++
 src/ui/vektorcanvas.c              | 43 +++++++++++++++++++++++++-----
 src/ui/vektorcanvas.h              |  2 ++
 5 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/src/application/applicationstate.c b/src/application/applicationstate.c
index c75354d..fb3c9c5 100644
--- a/src/application/applicationstate.c
+++ b/src/application/applicationstate.c
@@ -1,3 +1,4 @@
+#include "src/core/matrix.h"
 #include "src/ui/uicontroller.h"
 #include "stdlib.h"
 
@@ -232,6 +233,8 @@ void vektor_appstate_new(VektorWidgetState* wstate, VektorAppState* stateOut) {
     stateOut->currentColor = vektor_color_solid(0, 0, 0);
     stateOut->selectedShape = NULL;
     VektorCanvasRenderInfo* renderInfo = malloc(sizeof(VektorCanvasRenderInfo));
+    renderInfo->zoom = 1;
+    m33_to_gl4(m33_identity(), renderInfo->canvasTransform);
     renderInfo->selectedShape = &(stateOut->selectedShape);
     renderInfo->shapes = stateOut->shapeBuffer;
     renderInfo->startupTime = stateOut->startupTime;
diff --git a/src/core/matrix.c b/src/core/matrix.c
index 3ab914e..a262e62 100644
--- a/src/core/matrix.c
+++ b/src/core/matrix.c
@@ -87,3 +87,25 @@ V2 m33_transform(const M33 mat, const V2 v) {
     return (V2){mat.m[0][0] * v.x + mat.m[0][1] * v.y + mat.m[0][2],
                 mat.m[1][0] * v.x + mat.m[1][1] * v.y + mat.m[1][2]};
 }
+
+void m33_to_gl4(const M33 m, float out[16]) {
+    out[0] = m.m[0][0];
+    out[1] = m.m[1][0];
+    out[2] = 0.0f;
+    out[3] = 0.0f;
+
+    out[4] = m.m[0][1];
+    out[5] = m.m[1][1];
+    out[6] = 0.0f;
+    out[7] = 0.0f;
+
+    out[8] = 0.0f;
+    out[9] = 0.0f;
+    out[10] = 1.0f;
+    out[11] = 0.0f;
+
+    out[12] = m.m[0][2];
+    out[13] = m.m[1][2];
+    out[14] = 0.0f;
+    out[15] = 1.0f;
+}
\ No newline at end of file
diff --git a/src/core/matrix.h b/src/core/matrix.h
index 10a47f1..c919528 100644
--- a/src/core/matrix.h
+++ b/src/core/matrix.h
@@ -22,4 +22,6 @@ M33 m33_inverse(const M33 m);
 
 V2 m33_transform(const M33 mat, const V2 v);
 
+void m33_to_gl4(const M33 m, float out[16]);
+
 #endif // MATRIX_H_
diff --git a/src/ui/vektorcanvas.c b/src/ui/vektorcanvas.c
index c10a427..7b38c1c 100644
--- a/src/ui/vektorcanvas.c
+++ b/src/ui/vektorcanvas.c
@@ -3,6 +3,7 @@
 #include "gtk/gtk.h"
 
 #include "../core/raster.h"
+#include "src/core/matrix.h"
 #include "src/core/primitives.h"
 #include "src/util/color.h"
 #include "uicontroller.h"
@@ -158,10 +159,10 @@ static gboolean render(GtkGLArea* a, GdkGLContext* ctx,
     // PASS 1 - draw shape vertices
     glUseProgram(standard_shader_program);
 
-    float projectionMatrix[16] = {1, 0, 0, 0, 0, 1, 0, 0,
-                                  0, 0, 1, 0, 0, 0, 0, 1};
+    // float projectionMatrix[16] = {1, 0, 0, 0, 0, 1, 0, 0,
+    //                               0, 0, 1, 0, 0, 0, 0, 1};
     glUniformMatrix4fv(shader_standard_uProjMatrixLoc, 1, GL_FALSE,
-                       projectionMatrix);
+                       renderInfo->canvasTransform);
 
     glBindVertexArray(vao);
     glDisable(GL_CULL_FACE);
@@ -182,11 +183,8 @@ static gboolean render(GtkGLArea* a, GdkGLContext* ctx,
 
         glUseProgram(selection_shader_program);
 
-        float projectionMatrix[16] = {1, 0, 0, 0, 0, 1, 0, 0,
-                                      0, 0, 1, 0, 0, 0, 0, 1};
-
         glUniformMatrix4fv(shader_selection_uProjMatrixLoc, 1, GL_FALSE,
-                           projectionMatrix);
+                           renderInfo->canvasTransform);
         glUniform1f(shader_selection_uTimeLoc, time);
         glUniform2f(shader_selection_uMinLoc, bbox.min.x, bbox.min.y);
         glUniform2f(shader_selection_uMaxLoc, bbox.max.x, bbox.max.y);
@@ -241,6 +239,30 @@ static void realize(GtkGLArea* area, gpointer user_data) {
     init_geometry();
 }
 
+static void on_scroll(GtkEventControllerScroll* controller, double dx,
+                      double dy, gpointer user_data) {
+    VektorCanvasRenderInfo* s = user_data;
+
+    GdkModifierType state = gtk_event_controller_get_current_event_state(
+        GTK_EVENT_CONTROLLER(controller));
+
+    if (state & GDK_CONTROL_MASK) {
+
+        if (dy < 0)
+            s->zoom *= 0.9f;
+        else if (dy > 0)
+            s->zoom *= 1.1f;
+
+        M33 mat = m33_scale(s->zoom, s->zoom);
+
+        m33_to_gl4(mat, s->canvasTransform);
+
+        GtkWidget* widget =
+            gtk_event_controller_get_widget(GTK_EVENT_CONTROLLER(controller));
+        gtk_gl_area_queue_render(GTK_GL_AREA(widget));
+    }
+}
+
 void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut,
                         VektorCanvasRenderInfo* renderInfo) {
     canvasOut->canvasWidget = state->workspaceCanvas;
@@ -258,4 +280,11 @@ void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut,
                      NULL);
     g_signal_connect(canvasOut->canvasWidget, "render", G_CALLBACK(render),
                      renderInfo);
+
+    GtkEventController* scroll =
+        gtk_event_controller_scroll_new(GTK_EVENT_CONTROLLER_SCROLL_VERTICAL);
+
+    gtk_widget_add_controller(GTK_WIDGET(canvasOut->canvasWidget), scroll);
+
+    g_signal_connect(scroll, "scroll", G_CALLBACK(on_scroll), renderInfo);
 }
diff --git a/src/ui/vektorcanvas.h b/src/ui/vektorcanvas.h
index 540e000..e70c05e 100644
--- a/src/ui/vektorcanvas.h
+++ b/src/ui/vektorcanvas.h
@@ -25,6 +25,8 @@ typedef struct VektorCanvasRenderInfo {
 
     // a pointer to appstate->selectedShape
     VektorShape** selectedShape;
+    float zoom;
+    float canvasTransform[16];
 } VektorCanvasRenderInfo;
 
 void vektor_canvas_init(VektorWidgetState* state, VektorCanvas* canvasOut,