110 lines
2.8 KiB
Go
110 lines
2.8 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package asset
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/*
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#cgo LDFLAGS: -landroid
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#include <android/asset_manager.h>
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#include <android/asset_manager_jni.h>
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#include <jni.h>
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#include <stdlib.h>
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static AAssetManager* asset_manager_init(uintptr_t java_vm, uintptr_t jni_env, jobject ctx) {
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JavaVM* vm = (JavaVM*)java_vm;
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JNIEnv* env = (JNIEnv*)jni_env;
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// Equivalent to:
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// assetManager = ctx.getResources().getAssets();
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jclass ctx_clazz = (*env)->FindClass(env, "android/content/Context");
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jmethodID getres_id = (*env)->GetMethodID(env, ctx_clazz, "getResources", "()Landroid/content/res/Resources;");
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jobject res = (*env)->CallObjectMethod(env, ctx, getres_id);
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jclass res_clazz = (*env)->FindClass(env, "android/content/res/Resources");
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jmethodID getam_id = (*env)->GetMethodID(env, res_clazz, "getAssets", "()Landroid/content/res/AssetManager;");
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jobject am = (*env)->CallObjectMethod(env, res, getam_id);
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// Pin the AssetManager and load an AAssetManager from it.
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am = (*env)->NewGlobalRef(env, am);
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return AAssetManager_fromJava(env, am);
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}
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*/
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import "C"
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import (
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"fmt"
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"io"
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"log"
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"os"
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"sync"
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"unsafe"
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"golang.org/x/mobile/internal/mobileinit"
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)
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var assetOnce sync.Once
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// asset_manager is the asset manager of the app.
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var assetManager *C.AAssetManager
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func assetInit() {
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err := mobileinit.RunOnJVM(func(vm, env, ctx uintptr) error {
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assetManager = C.asset_manager_init(C.uintptr_t(vm), C.uintptr_t(env), C.jobject(ctx))
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return nil
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})
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if err != nil {
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log.Fatalf("asset: %v", err)
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}
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}
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func openAsset(name string) (File, error) {
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assetOnce.Do(assetInit)
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cname := C.CString(name)
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defer C.free(unsafe.Pointer(cname))
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a := &asset{
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ptr: C.AAssetManager_open(assetManager, cname, C.AASSET_MODE_UNKNOWN),
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name: name,
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}
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if a.ptr == nil {
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return nil, a.errorf("open", "bad asset")
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}
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return a, nil
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}
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type asset struct {
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ptr *C.AAsset
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name string
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}
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func (a *asset) errorf(op string, format string, v ...interface{}) error {
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return &os.PathError{
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Op: op,
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Path: a.name,
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Err: fmt.Errorf(format, v...),
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}
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}
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func (a *asset) Read(p []byte) (n int, err error) {
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n = int(C.AAsset_read(a.ptr, unsafe.Pointer(&p[0]), C.size_t(len(p))))
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if n == 0 && len(p) > 0 {
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return 0, io.EOF
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}
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if n < 0 {
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return 0, a.errorf("read", "negative bytes: %d", n)
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}
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return n, nil
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}
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func (a *asset) Seek(offset int64, whence int) (int64, error) {
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// TODO(crawshaw): use AAsset_seek64 if it is available.
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off := C.AAsset_seek(a.ptr, C.off_t(offset), C.int(whence))
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if off == -1 {
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return 0, a.errorf("seek", "bad result for offset=%d, whence=%d", offset, whence)
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}
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return int64(off), nil
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}
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func (a *asset) Close() error {
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C.AAsset_close(a.ptr)
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return nil
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}
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