Where do I point my freetype font loader to?

问题

I have successfully put my font onto the apk in the assets/ folder of my apk. I'm currently trying to get the Freetype library to see the Arial.ttf inside of the folder, but it can't find it.

APK structure:

apk/
    AndroidManifest.xml
    assets/
        Arial.ttf
    classes.dex
    lib/
    META-INF/
    res/
    resources.arsc

Loading the font:

FT_Face face;
if (FT_New_Face(ft, "/assets/Arial.ttf", 0, &face)) // TODO: get font locally
    __android_log_print(ANDROID_LOG_INFO, "SetupGlyphs", "ERROR::FREETYPE: Failed to load font.");

回答1:

Assets are files on the development machine. They are not files on the device. They are entries in the ZIP archive that is the APK.

In Java code (most likely), you will need to copy the asset (from AssetManager) to a local file on the filesystem, then have your native code use that local filesystem copy.

For example, this activity, copies a PDF from an asset to internal storage, to be able to view it using FileProvider and a third-party PDF viewer:

/***
  Copyright (c) 2013 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    https://commonsware.com/Android
 */

package com.commonsware.android.cp.v4file;

import android.app.Activity;
import android.content.Intent;
import android.content.res.AssetManager;
import android.os.Bundle;
import android.support.v4.content.FileProvider;
import android.util.Log;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class FilesCPDemo extends Activity {
  private static final String AUTHORITY="com.commonsware.android.cp.v4file";

  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);

    File f=new File(getFilesDir(), "test.pdf");

    if (!f.exists()) {
      AssetManager assets=getResources().getAssets();

      try {
        copy(assets.open("test.pdf"), f);
      }
      catch (IOException e) {
        Log.e("FileProvider", "Exception copying from assets", e);
      }
    }

    Intent i=
        new Intent(Intent.ACTION_VIEW,
                   FileProvider.getUriForFile(this, AUTHORITY, f));

    i.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    startActivity(i);
    finish();
  }

  static private void copy(InputStream in, File dst) throws IOException {
    FileOutputStream out=new FileOutputStream(dst);
    byte[] buf=new byte[1024];
    int len;

    while ((len=in.read(buf)) > 0) {
      out.write(buf, 0, len);
    }

    in.close();
    out.close();
  }
}

In your case, you would do this work before starting your JNI code that requires the font. And, since the path might vary from device to device or user to user, pass in the path to the font to your JNI code, rather than trying to hard-code it in the C/C++.

来源：https://stackoverflow.com/questions/38127111/where-do-i-point-my-freetype-font-loader-to

标签

android

android-ndk

freetype

freetype2