sdl: video, render: Update error handling; Add SetError() and INIT_EVENTS

Author: malashin

BREAKING.md

@@ -2,7 +2,8 @@
 
 ### v0.2..master
 
-+ Renamed `Texture.GL_BindTexture()` and `Texture.GL_UnbindTexture()` to `Texture.GLBind()` and `Texture.GLUnbind()` respectively
++ Renamed `Texture.GL_BindTexture()` to `Texture.GLBind()`
++ Renamed `Texture.GL_UnbindTexture()` to `Texture.GLUnbind()`
 + Renamed `LoadWAV_RW()` to `LoadWAVRW()`
 + Renamed `TouchId` to `TouchID` in `MultiGestureEvent` struct
 + Renamed `Unicode` to `unused` in `Keysym` struct (must have been a typo)
@@ -53,10 +54,18 @@
 + Renamed `QuickLoad_WAV()` to `QuickLoadWAV()`
 + Renamed `QuickLoad_RAW()` to `QuickLoadRAW()`
 + Moved error to the last return value in `ShowMessageBox()`
-+ Change Mutex, Sem, Cond to have methods instead of functions
-+ Merge `KeyUpEvent` and `KeyDownEvent` into `KeyboardEvent`
++ Changed Mutex, Sem, Cond to have methods instead of functions
++ Merged `KeyUpEvent` and `KeyDownEvent` into `KeyboardEvent`
 + Haptic functions now return bool and/or error instead of int
-+ Change `GameControllerMapping()` into `GameController.Mapping()`
++ Changed `GameControllerMapping()` into `GameController.Mapping()`
++ `GetDisplayName()` returns (string, error) instead of string
++ `GetCurrentVideoDriver()` returns (string, error) instead of string
++ `Window.Destroy()` returns error
++ `Window.GetID()` returns (uint32, error) instead of uint32
++ `GetNumRenderDrivers()` returns (int, error) instead of int
++ `GetRenderDriverInfo()` returns (int, error) instead of int
++ `Texture.Destroy()` returns error
++ `Renderer.Destroy()` returns error
 
 - Unexported `Padding` in `AudioSpec` struct
 - Unexported `goHintCallback`

sdl/error.go

@@ -1,5 +1,12 @@
 package sdl
 
+/*
+#include "sdl_wrapper.h"
+
+void GoSetError(const char *fmt) {
+  SDL_SetError("%s", fmt);
+}
+*/
 // #include "sdl_wrapper.h"
 import "C"
 import "errors"
@@ -35,6 +42,16 @@ func GetError() error {
 	return nil
 }
 
+// SetError set the SDL error message.
+// (https://wiki.libsdl.org/SDL_SetError)
+func SetError(err error) {
+	if err != nil {
+		C.GoSetError(C.CString(err.Error()))
+		return
+	}
+	C.GoSetError(nil)
+}
+
 // ClearError clears any previous error message.
 // (https://wiki.libsdl.org/SDL_ClearError)
 func ClearError() {

sdl/events.go

@@ -627,7 +627,7 @@ func goEvent(cevent *CEvent) Event {
 		return (*DollarGestureEvent)(unsafe.Pointer(cevent))
 	case DROPFILE, DROPTEXT, DROPBEGIN, DROPCOMPLETE:
 		e := (*tDropEvent)(unsafe.Pointer(cevent))
-		event := DropEvent{Type: e.Type, Timestamp: e.Timestamp, File: string(C.GoString((*C.char)(e.File))), WindowID: e.WindowID}
+		event := DropEvent{Type: e.Type, Timestamp: e.Timestamp, File: C.GoString((*C.char)(e.File)), WindowID: e.WindowID}
 		C.SDL_free(e.File)
 		return &event
 	case RENDER_TARGETS_RESET, RENDER_DEVICE_RESET: