ebiten/internal/graphicsdriver/opengl/gl/conversions_windows.go

97 lines
2.3 KiB
Go

// SPDX-License-Identifier: MIT
package gl
import (
"fmt"
"reflect"
"runtime"
"strings"
"unsafe"
)
// Ptr takes a slice or pointer (to a singular scalar value or the first
// element of an array or slice) and returns its GL-compatible address.
//
// For example:
//
// var data []uint8
// ...
// gl.TexImage2D(gl.TEXTURE_2D, ..., gl.UNSIGNED_BYTE, gl.Ptr(&data[0]))
func Ptr(data interface{}) unsafe.Pointer {
if data == nil {
return unsafe.Pointer(nil)
}
var addr unsafe.Pointer
switch v := data.(type) {
case *uint8:
addr = unsafe.Pointer(v)
case *uint16:
addr = unsafe.Pointer(v)
case *float32:
addr = unsafe.Pointer(v)
case []uint8:
addr = unsafe.Pointer(&v[0])
case []uint16:
addr = unsafe.Pointer(&v[0])
case []float32:
addr = unsafe.Pointer(&v[0])
default:
panic(fmt.Errorf("unsupported type %T; must be a slice or pointer to a singular scalar value or the first element of an array or slice", v))
}
return addr
}
// Str takes a null-terminated Go string and returns its GL-compatible address.
// This function reaches into Go string storage in an unsafe way so the caller
// must ensure the string is not garbage collected.
func Str(str string) *uint8 {
if !strings.HasSuffix(str, "\x00") {
panic("str argument missing null terminator: " + str)
}
header := (*reflect.StringHeader)(unsafe.Pointer(&str))
return (*uint8)(unsafe.Pointer(header.Data))
}
// GoStr takes a null-terminated string returned by OpenGL and constructs a
// corresponding Go string.
func GoStr(cstr *uint8) string {
str := ""
for {
if *cstr == 0 {
break
}
str += string(*cstr)
cstr = (*uint8)(unsafe.Pointer(uintptr(unsafe.Pointer(cstr)) + 1))
}
return str
}
// Strs takes a list of Go strings (with or without null-termination) and
// returns their C counterpart.
//
// The returned free function must be called once you are done using the strings
// in order to free the memory.
//
// If no strings are provided as a parameter this function will panic.
func Strs(strs ...string) (cstrs **uint8, free func()) {
if len(strs) == 0 {
panic("Strs: expected at least 1 string")
}
var pinned []string
var ptrs []*uint8
for _, str := range strs {
if !strings.HasSuffix(str, "\x00") {
str += "\x00"
}
pinned = append(pinned, str)
ptrs = append(ptrs, Str(str))
}
return &ptrs[0], func() {
runtime.KeepAlive(pinned)
pinned = nil
}
}