Refactor mapping to the native structs

Author: SpaiR

README.md

@@ -241,6 +241,10 @@ Dear ImGui by default uses a stb_strutype library to render a fonts atlas. It's
 * To get an input/output to/from Dear ImGui - use primitive wrappers: `ImBool`, `ImInt` etc.
 * Due to the Java and JNI restrictions we can't provide a fully fledged callbacks to the `ImGui::InputText` methods.
   To replace some features use an ImGuiInputTextData class.
+* All classes which are represent Dear ImGui structs have a field with a pointer to those structs.
+  Field is public and could be modified without restrictions. So by changing the pointer it's possible to use the same java class to modify different
+  native structs. Commonly you don't need to mind about that.
+  Just keep in mind that you are able to do advanced stuff with it like: save pointers to the structs to modify them later. 
 * Read [javadoc](https://javadoc.io/doc/io.imgui.java/binding) and sources comments to get more info.
 
 ## How to Build

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

@@ -1,5 +1,7 @@
 package imgui;
 
+import imgui.binding.ImGuiStruct;
+
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
@@ -11,36 +13,28 @@
  * BINDING NOTICE: Since it's impossible to do a 1:1 mapping with JNI, current class provides "getCmdList*()" methods.
  * Those are used to get the data needed to do a rendering.
  */
-public final class ImDrawData {
+public final class ImDrawData extends ImGuiStruct {
     public static final int SIZEOF_IM_DRAW_IDX = 2;
     public static final int SIZEOF_IM_DRAW_VERT = (4 + 1) * 4;
 
     private static final int FACTOR = 5_000;
 
-    final long ptr;
-
     private ByteBuffer idxBuffer = ByteBuffer.allocateDirect(SIZEOF_IM_DRAW_IDX * FACTOR).order(ByteOrder.nativeOrder());
     private ByteBuffer vtxBuffer = ByteBuffer.allocateDirect(SIZEOF_IM_DRAW_VERT * FACTOR).order(ByteOrder.nativeOrder());
 
-    ImDrawData(final long ptr) {
-        this.ptr = ptr;
+    public ImDrawData(final long ptr) {
+        super(ptr);
     }
 
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
         #include "jni_common.h"
+        #include "jni_binding_struct.h"
 
-        jfieldID imDrawDataPtrID;
-
-        #define IM_DRAW_DATA ((ImDrawData*)env->GetLongField(object, imDrawDataPtrID))
+        #define IM_DRAW_DATA ((ImDrawData*)STRUCT_PTR)
      */
 
-    static native void nInit(); /*
-        jclass jImDrawDataClass = env->FindClass("imgui/ImDrawData");
-        imDrawDataPtrID = env->GetFieldID(jImDrawDataClass, "ptr", "J");
-    */
-
     ///////// Start of Render Methods | Binding
 
     /**

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

@@ -1,5 +1,7 @@
 package imgui;
 
+import imgui.binding.ImGuiStruct;
+
 /**
  * Draw command list
  * This is the low-level list of polygons that ImGui:: functions are filling. At the end of the frame,
@@ -11,28 +13,20 @@
  * but you are totally free to apply whatever transformation matrix to want to the data (if you apply such transformation you'll want to apply it to ClipRect as well)
  * Important: Primitives are always added to the list and not culled (culling is done at higher-level by ImGui:: functions), if you use this API a lot consider coarse culling your drawn objects.
  */
-public final class ImDrawList {
-    long ptr;
-
-    ImDrawList(final long ptr) {
-        this.ptr = ptr;
+public final class ImDrawList extends ImGuiStruct {
+    public ImDrawList(final long ptr) {
+        super(ptr);
     }
 
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
         #include "jni_common.h"
+        #include "jni_binding_struct.h"
 
-        jfieldID imDrawListPtrID;
-
-        #define IM_DRAW_LIST ((ImDrawList*)env->GetLongField(object, imDrawListPtrID))
+        #define IM_DRAW_LIST ((ImDrawList*)STRUCT_PTR)
      */
 
-    static native void nInit(); /*
-        jclass jImDrawListClass = env->FindClass("imgui/ImDrawList");
-        imDrawListPtrID = env->GetFieldID(jImDrawListClass, "ptr", "J");
-    */
-
     /**
      * Flags, you may poke into these to adjust anti-aliasing settings per-primitive.
      */

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

@@ -1,54 +1,37 @@
 package imgui;
 
+import imgui.binding.ImGuiStructDestroyable;
+
 /**
  * Font runtime data and rendering
  * ImFontAtlas automatically loads a default embedded font for you when you call GetTexDataAsAlpha8() or GetTexDataAsRGBA32().
  */
-public final class ImFont implements ImGuiDestroyableStruct {
-    final long ptr;
-
+public final class ImFont extends ImGuiStructDestroyable {
     private ImFontGlyph fallbackGlyph = null;
 
-    /**
-     * This class will create a native structure.
-     * Call {@link #destroy()} method to manually free used memory.
-     */
     public ImFont() {
-        ImGui.touch();
-        ptr = nCreate();
     }
 
-    ImFont(final long ptr) {
-        this.ptr = ptr;
-    }
-
-    @Override
-    public void destroy() {
-        nDestroy(ptr);
+    public ImFont(final long ptr) {
+        super(ptr);
     }
 
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
         #include "jni_common.h"
+        #include "jni_binding_struct.h"
 
-        jfieldID imFontPtrID;
-
-        #define IM_FONT ((ImFont*)env->GetLongField(object, imFontPtrID))
+        #define IM_FONT ((ImFont*)STRUCT_PTR)
      */
 
-    static native void nInit(); /*
-        jclass jImFontClass = env->FindClass("imgui/ImFont");
-        imFontPtrID = env->GetFieldID(jImFontClass, "ptr", "J");
-    */
+    @Override
+    protected long create() {
+        return nCreate();
+    }
 
     private native long nCreate(); /*
-        ImFont* imFont = new ImFont();
-        return (intptr_t)imFont;
-    */
-
-    private native void nDestroy(long ptr); /*
-        delete (ImFont*)ptr;
+        return (intptr_t)(new ImFont());
     */
 
     // TODO IndexAdvanceX

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

@@ -1,5 +1,6 @@
 package imgui;
 
+import imgui.binding.ImGuiStructDestroyable;
 import imgui.type.ImInt;
 
 import java.nio.ByteBuffer;
@@ -24,57 +25,42 @@
  * - Even though many functions are suffixed with "TTF", OTF data is supported just as well.
  * - This is an old API and it is currently awkward for those and and various other reasons! We will address them in the future!
  */
-public final class ImFontAtlas implements ImGuiDestroyableStruct {
-    final long ptr;
-
+public final class ImFontAtlas extends ImGuiStructDestroyable {
     private ByteBuffer alpha8pixels = null;
     private ByteBuffer rgba32pixels = null;
 
-    /**
-     * This class will create a native structure.
-     * Call {@link #destroy()} method to manually free used memory.
-     */
     public ImFontAtlas() {
-        ImGui.touch();
-        ptr = nCreate();
     }
 
-    ImFontAtlas(final long ptr) {
-        this.ptr = ptr;
-    }
-
-    @Override
-    public void destroy() {
-        nDestroy(ptr);
+    public ImFontAtlas(final long ptr) {
+        super(ptr);
     }
 
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
+        #include "jni_binding_struct.h"
 
-        jfieldID imFontAtlasPtrID;
-
-        #define IM_FONT_ATLAS ((ImFontAtlas*)env->GetLongField(object, imFontAtlasPtrID))
+        #define IM_FONT_ATLAS ((ImFontAtlas*)STRUCT_PTR)
 
         jmethodID jImFontAtlasCreateAlpha8PixelsMID;
         jmethodID jImFontAtlasCreateRgba32PixelsMID;
      */
 
     static native void nInit(); /*
         jclass jImFontAtlasClass = env->FindClass("imgui/ImFontAtlas");
-        imFontAtlasPtrID = env->GetFieldID(jImFontAtlasClass, "ptr", "J");
 
         jImFontAtlasCreateAlpha8PixelsMID = env->GetMethodID(jImFontAtlasClass, "createAlpha8Pixels", "(I)Ljava/nio/ByteBuffer;");
         jImFontAtlasCreateRgba32PixelsMID = env->GetMethodID(jImFontAtlasClass, "createRgba32Pixels", "(I)Ljava/nio/ByteBuffer;");
     */
 
-    private native long nCreate(); /*
-        ImFontAtlas* imFontAtlas = new ImFontAtlas();
-        return (intptr_t)imFontAtlas;
-    */
+    @Override
+    protected long create() {
+        return nCreate();
+    }
 
-    private native void nDestroy(long ptr); /*
-        delete (ImFontAtlas*)ptr;
+    private native long nCreate(); /*
+        return (intptr_t)(new ImFontConfig());
     */
 
     public ImFont addFont(final ImFontConfig imFontConfig) {

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

@@ -1,52 +1,40 @@
 package imgui;
 
-public final class ImFontConfig implements ImGuiDestroyableStruct {
-    final long ptr;
+import imgui.binding.ImGuiStructDestroyable;
 
+public final class ImFontConfig extends ImGuiStructDestroyable {
     private short[] glyphRanges;
 
     /**
      * This class will create a native structure.
      * Call {@link #destroy()} method to manually free used memory.
      */
     public ImFontConfig() {
-        ImGui.touch();
-        ptr = nCreate();
+        super();
         setFontDataOwnedByAtlas(false); // Read method javadoc
     }
 
     ImFontConfig(final long ptr) {
-        this.ptr = ptr;
+        super(ptr);
         setFontDataOwnedByAtlas(false); // Read method javadoc
     }
 
-    @Override
-    public void destroy() {
-        nDestroy(ptr);
-    }
-
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
         #include "jni_common.h"
+        #include "jni_binding_struct.h"
 
-        jfieldID imFontConfigPtrID;
-
-        #define IM_FONT_CONFIG ((ImFontConfig*)env->GetLongField(object, imFontConfigPtrID))
+        #define IM_FONT_CONFIG ((ImFontConfig*)STRUCT_PTR)
      */
 
-    static native void nInit(); /*
-        jclass jImFontConfigClass = env->FindClass("imgui/ImFontConfig");
-        imFontConfigPtrID = env->GetFieldID(jImFontConfigClass, "ptr", "J");
-    */
+    @Override
+    protected long create() {
+        return nCreate();
+    }
 
     private native long nCreate(); /*
-        ImFontConfig* imFontConfig = new ImFontConfig();
-        return (intptr_t)imFontConfig;
-    */
-
-    private native void nDestroy(long ptr); /*
-        delete (ImFontConfig*)ptr;
+        return (intptr_t)(new ImFontConfig());
     */
 
     /**

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

@@ -1,51 +1,34 @@
 package imgui;
 
+import imgui.binding.ImGuiStructDestroyable;
+
 /**
  * Hold rendering data for one glyph.
  * (Note: some language parsers may fail to convert the 31+1 bitfield members, in this case maybe drop store a single u32 or we can rework this)
  */
-public final class ImFontGlyph implements ImGuiDestroyableStruct {
-    final long ptr;
-
-    /**
-     * This class will create a native structure.
-     * Call {@link #destroy()} method to manually free used memory.
-     */
+public final class ImFontGlyph extends ImGuiStructDestroyable {
     public ImFontGlyph() {
-        ImGui.touch();
-        ptr = nCreate();
     }
 
-    ImFontGlyph(final long ptr) {
-        this.ptr = ptr;
-    }
-
-    @Override
-    public void destroy() {
-        nDestroy(ptr);
+    public ImFontGlyph(final long ptr) {
+        super(ptr);
     }
 
     /*JNI
         #include <stdint.h>
         #include <imgui.h>
+        #include "jni_binding_struct.h"
 
-        jfieldID imFontGlyphPtrID;
-
-        #define IM_FONT_GLYPH ((ImFontGlyph*)env->GetLongField(object, imFontGlyphPtrID))
+        #define IM_FONT_GLYPH ((ImFontGlyph*)STRUCT_PTR)
      */
 
-    static native void nInit(); /*
-        jclass jImFontGlyphClass = env->FindClass("imgui/ImFontGlyph");
-        imFontGlyphPtrID = env->GetFieldID(jImFontGlyphClass, "ptr", "J");
-    */
+    @Override
+    protected long create() {
+        return nCreate();
+    }
 
     private native long nCreate(); /*
-        ImFontConfig* imFontConfig = new ImFontConfig();
-        return (intptr_t)imFontConfig;
-    */
-
-    private native void nDestroy(long ptr); /*
-        delete (ImFontConfig*)ptr;
+        return (intptr_t)(new ImFontGlyph());
     */
 
     /**