perf: trim malloc heap after clearing canvas

this also applies when clearing layers

Author: vani-tty1

src/meme-core.c

@@ -1,5 +1,20 @@
 #include "meme-core.h"
 #include <MagickWand/MagickWand.h>
+#include <malloc.h>
+
+static guint release_memory_id = 0;
+
+static gboolean release_memory_cb (gpointer data) {
+    release_memory_id = 0;
+    malloc_trim (0);
+    return G_SOURCE_REMOVE;
+}
+
+void meme_release_memory (void) {
+    if (release_memory_id)
+        g_source_remove (release_memory_id);
+    release_memory_id = g_timeout_add (300, release_memory_cb, NULL);
+}
 
 ImageLayer * meme_layer_copy (const ImageLayer *src) {
     ImageLayer *dst = g_new0 (ImageLayer, 1);

src/meme-core.h

@@ -69,6 +69,7 @@ ImageLayer *meme_layer_copy (const ImageLayer *src);
 void meme_layer_free (gpointer data);
 GList *meme_layer_list_copy (GList *src);
 void meme_layer_list_free (GList *list);
+void meme_release_memory (void);
 void meme_magick_init (void);
 
 GdkPixbuf *meme_core_apply_effects(GdkPixbuf *composite, gboolean cinematic, gboolean deep_fry);

src/meme-window-layers.c

@@ -194,5 +194,6 @@ void on_delete_layer_clicked (MemeWindow *self) {
         self->selected_layer = NULL;
         sync_ui_with_layer(self);
         render_meme(self);
+        meme_release_memory ();
     }
 }

src/meme-window.c

@@ -64,6 +64,7 @@ void on_clear_clicked (MemeWindow *self) {
     gtk_widget_set_sensitive(GTK_WIDGET(self->clear_button), FALSE);
     self->zoom_level = 1.0;
     gtk_widget_set_size_request(GTK_WIDGET(self->meme_preview), -1, -1); 
+    meme_release_memory ();
 }
 
 void on_copy_clipboard_clicked (MemeWindow *self) {