[gtk/fix-picking-with-transforms] Add a transform test

[Matthias Clasen <matthiasc src gnome org>]

commit 5be785bff8748d539ac48a3c00d4dd66578e933f
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed May 12 21:50:32 2021 -0400

    Add a transform test
    
    This reveals some issues with scale handling.

 tests/meson.build |   1 +
 tests/testzoom.c  | 276 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 277 insertions(+)
---
diff --git a/tests/meson.build b/tests/meson.build
index c0e5f836b0..8ea23bf3fd 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -115,6 +115,7 @@ gtk_tests = [
   ['testwindowdrag'],
   ['testinhibitshortcuts'],
   ['testtexthistory', ['../gtk/gtktexthistory.c']],
+  ['testzoom']
 ]
 
 if os_unix
diff --git a/tests/testzoom.c b/tests/testzoom.c
new file mode 100644
index 0000000000..2465ce2cb3
--- /dev/null
+++ b/tests/testzoom.c
@@ -0,0 +1,276 @@
+#include <gtk/gtk.h>
+
+typedef struct
+{
+  GtkWidget parent_instance;
+  GtkWidget *child;
+  float scale;
+  float angle;
+} GtkZoom;
+
+typedef struct
+{
+  GtkWidgetClass parent_class;
+} GtkZoomClass;
+
+enum {
+  PROP_0,
+  PROP_CHILD,
+  PROP_SCALE,
+  PROP_ANGLE,
+  NUM_PROPERTIES
+};
+
+static GParamSpec *props[NUM_PROPERTIES] = { NULL, };
+
+GType gtk_zoom_get_type (void);
+
+G_DEFINE_TYPE (GtkZoom, gtk_zoom, GTK_TYPE_WIDGET)
+
+static void
+gtk_zoom_init (GtkZoom *zoom)
+{
+  zoom->child = NULL;
+  zoom->scale = 1.0;
+  zoom->angle = 0.0;
+}
+
+static void
+gtk_zoom_dispose (GObject *object)
+{
+  GtkZoom *zoom = (GtkZoom *)object;
+
+  g_clear_pointer (&zoom->child, gtk_widget_unparent);
+
+  G_OBJECT_CLASS (gtk_zoom_parent_class)->dispose (object);
+}
+
+static void
+update_transform (GtkZoom *zoom)
+{
+  GtkLayoutManager *manager;
+  GtkLayoutChild *child;
+  GskTransform *transform;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (zoom));
+  child = gtk_layout_manager_get_layout_child (manager, zoom->child);
+
+  transform = NULL;
+  transform = gsk_transform_rotate (transform, zoom->angle);
+  transform = gsk_transform_scale (transform, zoom->scale, zoom->scale);
+  gtk_fixed_layout_child_set_transform (GTK_FIXED_LAYOUT_CHILD (child), transform);
+  gsk_transform_unref (transform);
+}
+
+static void
+gtk_zoom_set_scale (GtkZoom *zoom,
+                    float    scale)
+{
+
+  if (zoom->scale == scale)
+    return;
+
+  zoom->scale = scale;
+
+  update_transform (zoom);
+
+  g_object_notify_by_pspec (G_OBJECT (zoom), props[PROP_SCALE]);
+
+  gtk_widget_queue_resize (GTK_WIDGET (zoom));
+}
+
+static void
+gtk_zoom_set_angle (GtkZoom *zoom,
+                    float    angle)
+{
+
+  if (zoom->angle == angle)
+    return;
+
+  zoom->angle = angle;
+
+  update_transform (zoom);
+
+  g_object_notify_by_pspec (G_OBJECT (zoom), props[PROP_ANGLE]);
+
+  gtk_widget_queue_resize (GTK_WIDGET (zoom));
+}
+
+static void
+gtk_zoom_set_child (GtkZoom   *zoom,
+                    GtkWidget *child)
+{
+  g_clear_pointer (&zoom->child, gtk_widget_unparent);
+
+  zoom->child = child;
+
+  if (zoom->child)
+    gtk_widget_set_parent (zoom->child, GTK_WIDGET (zoom));
+
+  g_object_notify_by_pspec (G_OBJECT (zoom), props[PROP_CHILD]);
+}
+
+static void
+gtk_zoom_set_property (GObject      *object,
+                       guint         prop_id,
+                       const GValue *value,
+                       GParamSpec   *pspec)
+{
+  GtkZoom *zoom = (GtkZoom *)object;
+
+  switch (prop_id)
+    {
+    case PROP_SCALE:
+      gtk_zoom_set_scale (zoom, g_value_get_float (value));
+      break;
+
+    case PROP_ANGLE:
+      gtk_zoom_set_angle (zoom, g_value_get_float (value));
+      break;
+
+    case PROP_CHILD:
+      gtk_zoom_set_child (zoom, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_zoom_get_property (GObject    *object,
+                       guint       prop_id,
+                       GValue     *value,
+                       GParamSpec *pspec)
+{
+  GtkZoom *zoom = (GtkZoom *)object;
+
+  switch (prop_id)
+    {
+    case PROP_SCALE:
+      g_value_set_float (value, zoom->scale);
+      break;
+
+    case PROP_ANGLE:
+      g_value_set_float (value, zoom->angle);
+      break;
+
+    case PROP_CHILD:
+      g_value_set_object (value, zoom->child);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_zoom_class_init (GtkZoomClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  object_class->dispose = gtk_zoom_dispose;
+  object_class->set_property = gtk_zoom_set_property;
+  object_class->get_property = gtk_zoom_get_property;
+
+  props[PROP_SCALE] = g_param_spec_float ("scale", "", "",
+                                          0.0, 100.0, 1.0,
+                                          G_PARAM_READWRITE);
+
+  props[PROP_ANGLE] = g_param_spec_float ("angle", "", "",
+                                          0.0, 360.0, 1.0,
+                                          G_PARAM_READWRITE);
+
+  props[PROP_CHILD] = g_param_spec_object ("child", "", "",
+                                           GTK_TYPE_WIDGET,
+                                           G_PARAM_READWRITE);
+
+  g_object_class_install_properties (object_class, NUM_PROPERTIES, props);
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_FIXED_LAYOUT);
+}
+
+static GtkWidget *
+gtk_zoom_new (void)
+{
+  return g_object_new (gtk_zoom_get_type (), NULL);
+}
+
+int
+main (int argc, char *argv[])
+{
+  GtkWindow *window;
+  GtkWidget *zoom;
+  GtkWidget *box;
+  GtkWidget *grid;
+  GtkWidget *sw;
+  GtkWidget *scale;
+  GtkWidget *angle;
+  GtkWidget *child;
+  GtkAdjustment *adjustment;
+
+  gtk_init ();
+
+  window = GTK_WINDOW (gtk_window_new ());
+  gtk_window_set_default_size (GTK_WINDOW (window), 600, 400);
+  box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
+  gtk_window_set_child (window, box);
+
+  grid = gtk_grid_new ();
+  gtk_grid_set_column_spacing (GTK_GRID (grid), 10);
+
+  scale = gtk_scale_new_with_range (GTK_ORIENTATION_HORIZONTAL, 1.0, 10.0, 1.0);
+  gtk_widget_set_hexpand (scale, TRUE);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Scale"), 0, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), scale, 1, 0, 1, 1);
+
+  angle = gtk_scale_new_with_range (GTK_ORIENTATION_HORIZONTAL, 0.0, 360.0, 1.0);
+  gtk_scale_add_mark (GTK_SCALE (angle),  90.0, GTK_POS_BOTTOM, NULL);
+  gtk_scale_add_mark (GTK_SCALE (angle), 180.0, GTK_POS_BOTTOM, NULL);
+  gtk_scale_add_mark (GTK_SCALE (angle), 270.0, GTK_POS_BOTTOM, NULL);
+  gtk_widget_set_hexpand (angle, TRUE);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Angle"), 0, 1, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), angle, 1, 1, 1, 1);
+  gtk_box_append (GTK_BOX (box), grid);
+
+  sw = gtk_scrolled_window_new ();
+  gtk_widget_set_hexpand (sw, TRUE);
+  gtk_widget_set_vexpand (sw, TRUE);
+  gtk_box_append (GTK_BOX (box), sw);
+
+  zoom = gtk_zoom_new ();
+  gtk_widget_set_halign (zoom, GTK_ALIGN_CENTER);
+  gtk_widget_set_valign (zoom, GTK_ALIGN_CENTER);
+  gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (sw), zoom);
+
+  adjustment = gtk_range_get_adjustment (GTK_RANGE (scale));
+  g_object_bind_property (adjustment, "value",
+                          zoom, "scale",
+                          G_BINDING_DEFAULT);
+
+  adjustment = gtk_range_get_adjustment (GTK_RANGE (angle));
+  g_object_bind_property (adjustment, "value",
+                          zoom, "angle",
+                          G_BINDING_DEFAULT);
+
+  if (argc > 1)
+    {
+      GtkBuilder *builder = gtk_builder_new ();
+      gtk_builder_add_from_file (builder, argv[1], NULL);
+      child = GTK_WIDGET (gtk_builder_get_object (builder, "child"));
+      gtk_zoom_set_child ((GtkZoom *)zoom, child);
+      g_object_unref (builder);
+    }
+  else
+    gtk_zoom_set_child ((GtkZoom *)zoom, gtk_button_new_with_label ("Click me!"));
+
+  gtk_window_present (window);
+
+  while (g_list_model_get_n_items (gtk_window_get_toplevels ()) > 0)
+    g_main_context_iteration (NULL, TRUE);
+
+  return 0;
+}