added TGA.h/tga.cpp

inc/hgl/2d/TGA.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include<hgl/platform/Platform.h>
+namespace hgl
+{
+    namespace imgfmt
+    {
+        constexpr const uint TGA_IMAGE_TYPE_COLOR_MAP   =1;
+        constexpr const uint TGA_IMAGE_TYPE_TRUE_COLOR  =2;
+        constexpr const uint TGA_IMAGE_TYPE_GRAYSCALE   =3;
+
+        constexpr const uint TGA_DIRECTION_LOWER_LEFT   =0;
+        constexpr const uint TGA_DIRECTION_UPPER_LEFT   =1;
+
+#pragma pack(push,1)
+        struct TGAHeader
+        {
+            uint8 id;
+            uint8 color_map_type;
+            uint8 image_type;               // 1 colormap image ,2 true-color,3 grayscale
+
+            uint16 color_map_first;
+            uint16 color_map_length;
+            uint8 color_map_size;
+
+            uint16 x_origin;
+            uint16 y_origin;
+
+            uint16 width;
+            uint16 height;
+            uint8 bit;
+            uint8 image_desc;
+        };
+
+        union TGAImageDesc
+        {
+            uint8 image_desc;
+            struct
+            {
+                uint alpha_depth:4;
+                uint reserved:1;
+                uint direction:1;       //0 lower-left,1 upper left
+            };
+        };
+#pragma pack(pop)
+
+        constexpr size_t TGAHeaderSize=sizeof(TGAHeader);
+
+        bool FillTGAHeader(TGAHeader *header,const uint16 width,const uint16 height,const uint8 channels,const uint8 single_channel_bits=8);
+    }//namespace imgfmt
+}//namespace hgl

src/Bitmap/tga.cpp

@@ -0,0 +1,45 @@
+#include<hgl/2d/TGA.h>
+
+namespace hgl
+{
+    namespace imgfmt
+    {   
+        bool FillTGAHeader(TGAHeader *header,const uint16 width,const uint16 height,const uint8 channels,const uint8 single_channel_bits)
+        {
+            if(!header)return(false);
+            if(!width||!height)return(false);
+
+            if(channels!=1
+             &&channels!=3
+             &&channels!=4)return(false);
+
+            memset(header,0,sizeof(TGAHeader));
+
+            header->width=width;
+            header->height=height;
+
+            TGAImageDesc desc;
+
+            desc.image_desc=0;
+            
+            if(channels==1)
+            {
+                header->image_type=3;
+                header->bit=single_channel_bits;
+            }
+            else
+            {
+                header->image_type=2;
+                header->bit=channels*single_channel_bits;
+
+                if(channels==4)
+                    desc.alpha_depth=single_channel_bits;
+            }
+
+            desc.direction=TGA_DIRECTION_UPPER_LEFT;
+
+            header->image_desc=desc.image_desc;
+            return(true);
+        }
+    }//namespace imgfmt
+}//namespace hgl