[API] Remove lazy-created sructs and add methods to verify struct pointer

imgui-binding/src/main/java/imgui/ImFont.java

@@ -7,8 +7,8 @@ import imgui.binding.ImGuiStructDestroyable;
  * ImFontAtlas automatically loads a default embedded font for you when you call GetTexDataAsAlpha8() or GetTexDataAsRGBA32().
  */
 public final class ImFont extends ImGuiStructDestroyable {
-    private ImFontGlyph fallbackGlyph = null;
-    private ImFontGlyph foundGlyph = new ImFontGlyph(0);
+    private final ImFontGlyph fallbackGlyph = new ImFontGlyph(0);
+    private final ImFontGlyph foundGlyph = new ImFontGlyph(0);
 
     public ImFont() {
     }
@@ -64,9 +64,7 @@ public final class ImFont extends ImGuiStructDestroyable {
      * = FindGlyph(FontFallbackChar)
      */
     public ImFontGlyph getFallbackGlyph() {
-        if (fallbackGlyph == null) {
-            fallbackGlyph = new ImFontGlyph(nGetFallbackGlyphPtr());
-        }
+        fallbackGlyph.ptr = nGetFallbackGlyphPtr();
         return fallbackGlyph;
     }
 
@@ -172,11 +170,7 @@ public final class ImFont extends ImGuiStructDestroyable {
     // Methods
 
     public ImFontGlyph findGlyph(final int c) {
-        final long ptr = nFindGlyph(c);
-        if (ptr == 0) {
-            return null;
-        }
-        foundGlyph.ptr = ptr;
+        foundGlyph.ptr = nFindGlyph(c);
         return foundGlyph;
     }
 
@@ -185,11 +179,7 @@ public final class ImFont extends ImGuiStructDestroyable {
     */
 
     public ImFontGlyph findGlyphNoFallback(final int c) {
-        final long ptr = nFindGlyphNoFallback(c);
-        if (ptr == 0) {
-            return null;
-        }
-        foundGlyph.ptr = ptr;
+        foundGlyph.ptr = nFindGlyphNoFallback(c);
         return foundGlyph;
     }
 

imgui-binding/src/main/java/imgui/ImGui.java

@@ -32,11 +32,11 @@ public class ImGui {
     private static final ImGuiViewport WINDOW_VIEWPORT;
     private static final ImGuiViewport FIND_VIEWPORT;
 
-    private static ImDrawData drawData;
-    private static ImFont font;
-    private static ImGuiStyle style;
-    private static ImGuiViewport mainViewport;
-    private static ImGuiPlatformIO platformIO;
+    private static final ImDrawData DRAW_DATA;
+    private static final ImFont FONT;
+    private static final ImGuiStyle STYLE;
+    private static final ImGuiViewport MAIN_VIEWPORT;
+    private static final ImGuiPlatformIO PLATFORM_IO;
 
     static {
         final String libPath = System.getProperty(LIB_PATH_PROP);
@@ -61,6 +61,12 @@ public class ImGui {
         WINDOW_VIEWPORT = new ImGuiViewport(0);
         FIND_VIEWPORT = new ImGuiViewport(0);
 
+        DRAW_DATA = new ImDrawData(0);
+        FONT = new ImFont(0);
+        STYLE = new ImGuiStyle(0);
+        MAIN_VIEWPORT = new ImGuiViewport(0);
+        PLATFORM_IO = new ImGuiPlatformIO(0);
+
         nInitJni();
         ImFontAtlas.nInit();
         ImGuiPlatformIO.init();
@@ -164,10 +170,8 @@ public class ImGui {
      * Access the Style structure (colors, sizes). Always use PushStyleCol(), PushStyleVar() to modify style mid-frame!
      */
     public static ImGuiStyle getStyle() {
-        if (style == null) {
-            style = new ImGuiStyle(nGetStyle());
-        }
-        return style;
+        STYLE.ptr = nGetStyle();
+        return STYLE;
     }
 
     private static native long nGetStyle(); /*
@@ -200,10 +204,8 @@ public class ImGui {
      * Valid after Render() and until the next call to NewFrame(). this is what you have to render.
      */
     public static ImDrawData getDrawData() {
-        if (drawData == null) {
-            drawData = new ImDrawData(nGetDrawData());
-        }
-        return drawData;
+        DRAW_DATA.ptr = nGetDrawData();
+        return DRAW_DATA;
     }
 
     private static native long nGetDrawData(); /*
@@ -1094,10 +1096,8 @@ public class ImGui {
      * Get current font.
      */
     public static ImFont getFont() {
-        if (font == null) {
-            font = new ImFont(nGetFont());
-        }
-        return font;
+        FONT.ptr = nGetFont();
+        return FONT;
     }
 
     private static native long nGetFont(); /*
@@ -5121,10 +5121,8 @@ public class ImGui {
      * Return primary/default viewport.
      */
     public static ImGuiViewport getMainViewport() {
-        if (mainViewport == null) {
-            mainViewport = new ImGuiViewport(nGetMainViewport());
-        }
-        return mainViewport;
+        MAIN_VIEWPORT.ptr = nGetMainViewport();
+        return MAIN_VIEWPORT;
     }
 
     private static native long nGetMainViewport(); /*
@@ -5682,10 +5680,8 @@ public class ImGui {
      * Platform/renderer functions, for backend to setup + viewports list.
      */
     public static ImGuiPlatformIO getPlatformIO() {
-        if (platformIO == null) {
-            platformIO = new ImGuiPlatformIO(nGetPlatformIO());
-        }
-        return platformIO;
+        PLATFORM_IO.ptr = nGetPlatformIO();
+        return PLATFORM_IO;
     }
 
     private static native long nGetPlatformIO(); /*

imgui-binding/src/main/java/imgui/ImGuiIO.java

@@ -8,7 +8,7 @@ import imgui.callback.ImStrSupplier;
  * Access via ImGui::GetIO(). Read 'Programmer guide' section in .cpp file for general usage.
  */
 public final class ImGuiIO {
-    private ImFontAtlas imFontAtlas;
+    private final ImFontAtlas imFontAtlas = new ImFontAtlas(0);
 
     ImGuiIO() {
     }
@@ -240,9 +240,7 @@ public final class ImGuiIO {
      * Font atlas: load, rasterize and pack one or more fonts into a single texture.
      */
     public ImFontAtlas getFonts() {
-        if (imFontAtlas == null) {
-            imFontAtlas = new ImFontAtlas(nGetFonts());
-        }
+        imFontAtlas.ptr = nGetFonts();
         return imFontAtlas;
     }
 
@@ -256,7 +254,6 @@ public final class ImGuiIO {
      * BINDING NOTICE: You SHOULD manually destroy previously used ImFontAtlas.
      */
     public void setFonts(final ImFontAtlas imFontAtlas) {
-        this.imFontAtlas = imFontAtlas;
         nSetFonts(imFontAtlas.ptr);
     }
 

imgui-binding/src/main/java/imgui/binding/ImGuiStruct.java

@@ -3,11 +3,13 @@ package imgui.binding;
 import imgui.ImGui;
 
 /**
- * Class provides a communication layer between binding and Dear ImGui library though the "pointer" field.
+ * Class provides a communication layer between binding and Dear ImGui library through the "pointer" field.
  */
 public abstract class ImGuiStruct {
     /**
-     * Pointer to the natively allocated object,
+     * Pointer to the natively allocated object.
+     * Could be zero if JNI returned NULL instead of the real object.
+     * For such cases methods {@link #isValidPtr()} and {@link #isNotValidPtr()} could be used to verify that object points to the real object.
      */
     public long ptr;
 
@@ -15,4 +17,22 @@ public abstract class ImGuiStruct {
         ImGui.init();
         this.ptr = ptr;
     }
+
+    /**
+     * Shows if object pointer is valid and does it point to the existing object.
+     *
+     * @return true, if pointer is valid
+     */
+    public final boolean isValidPtr() {
+        return ptr != 0;
+    }
+
+    /**
+     * Shows if object pointer is valid and does it point to the existing object.
+     *
+     * @return true, if pointer is invalid
+     */
+    public final boolean isNotValidPtr() {
+        return !isValidPtr();
+    }
 }

imgui-binding/src/main/java/imgui/extension/imnodes/ImNodes.java

@@ -12,7 +12,7 @@ import imgui.type.ImInt;
  * Refer to the library's Github page for examples and support
  */
 public final class ImNodes {
-    private static ImNodesStyle style;
+    private static final ImNodesStyle STYLE = new ImNodesStyle(0);
 
     private ImNodes() {
     }
@@ -61,10 +61,8 @@ public final class ImNodes {
      * Returns the global style struct. See the struct declaration for default values.
      */
     public static ImNodesStyle getStyle() {
-        if (style == null) {
-            style = new ImNodesStyle(nGetStyle());
-        }
-        return style;
+        STYLE.ptr = nGetStyle();
+        return STYLE;
     }
 
     private static native long nGetStyle(); /*

imgui-binding/src/main/java/imgui/extension/imnodes/ImNodesContext.java

@@ -3,7 +3,6 @@ package imgui.extension.imnodes;
 import imgui.binding.ImGuiStructDestroyable;
 
 public final class ImNodesContext extends ImGuiStructDestroyable {
-
     public ImNodesContext() {
     }
 

imgui-binding/src/main/java/imgui/extension/nodeditor/NodeEditor.java

@@ -25,7 +25,7 @@ public final class NodeEditor {
     private static final ImDrawList HINT_BACKGROUND_DRAW_LIST = new ImDrawList(0);
     private static final ImDrawList NODE_BACKGROUND_DRAW_LIST = new ImDrawList(0);
 
-    private static NodeEditorStyle style;
+    private static final NodeEditorStyle STYLE = new NodeEditorStyle(0);
 
     private NodeEditor() {
     }
@@ -128,10 +128,8 @@ public final class NodeEditor {
     */
 
     public static NodeEditorStyle getStyle() {
-        if (style == null) {
-            style = new NodeEditorStyle(nGetStyle());
-        }
-        return style;
+        STYLE.ptr = nGetStyle();
+        return STYLE;
     }
 
     private static native long nGetStyle(); /*
@@ -198,13 +196,8 @@ public final class NodeEditor {
     }
 
     public static ImDrawList getNodeBackgroundDrawList(final long nodeId) {
-        final long ptr = nGetNodeBackgroundDrawList(nodeId);
-        if (ptr == 0) {
-            return null;
-        } else {
-            NODE_BACKGROUND_DRAW_LIST.ptr = ptr;
-            return NODE_BACKGROUND_DRAW_LIST;
-        }
+        NODE_BACKGROUND_DRAW_LIST.ptr = nGetNodeBackgroundDrawList(nodeId);
+        return NODE_BACKGROUND_DRAW_LIST;
     }
 
     private static native long nGetHintForegroundDrawList(); /*

imgui-binding/src/main/java/imgui/internal/ImGui.java

@@ -51,11 +51,7 @@ public final class ImGui extends imgui.ImGui {
     */
 
     public static ImGuiDockNode dockBuilderGetNode(final int nodeId) {
-        final long ptr = nDockBuilderGetNode(nodeId);
-        if (ptr == 0) {
-            return null;
-        }
-        DOCK_NODE.ptr = ptr;
+        DOCK_NODE.ptr = nDockBuilderGetNode(nodeId);
         return DOCK_NODE;
     }
 
@@ -64,11 +60,7 @@ public final class ImGui extends imgui.ImGui {
     */
 
     public static ImGuiDockNode dockBuilderGetCentralNode(final int nodeId) {
-        final long ptr = nDockBuilderGetCentralNode(nodeId);
-        if (ptr == 0) {
-            return null;
-        }
-        DOCK_NODE.ptr = ptr;
+        DOCK_NODE.ptr = nDockBuilderGetCentralNode(nodeId);
         return DOCK_NODE;
     }