java - 如何从 Bundle 中获取特定数据?
问题描述
我正在构建一个具有多个片段的应用程序,其中大约一半的片段包含一个用户可以用手指画线的视图(我们称之为画布)。我要做的是保存用户绘制的线条,然后将片段留给另一个片段并在该片段的画布上绘制一些线条,然后可以返回到前一个片段(第二个的绘图将得到已保存)该片段的绘图仅显示在画布中。如果用户返回到第二个片段,则只会显示第二个片段的绘图。我正在使用 Parcelable 接口。
我遇到的问题是来自一个片段的绘图将显示在不同的片段中,并且任何额外的线条都将显示在原始绘图的第一个片段中,我不知道如何解决这个问题。
片段 1
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
public class ChatFragment extends Fragment {
private PaintView paintView;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_chat, container, false);
paintView = v.findViewById(R.id.paintView1);
//I tried using this if statement to get the specific data
//Same for the other fragment
if (savedInstanceState != null) {
if (savedInstanceState.containsKey("line test")) {
paintView.setPaths(savedInstanceState.<FingerPath>getParcelableArrayList("chat test"));
}
}
DisplayMetrics metrics = new DisplayMetrics();
getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
paintView.init(metrics);
setHasOptionsMenu(true);
return v;
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.main, menu);
super.onCreateOptionsMenu(menu, inflater);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.normal:
paintView.normal();
return true;
case R.id.clear:
paintView.clear();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList("chat test", paintView.getPaths());
}
}
片段 2
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
public class LineLHwFragment extends Fragment {
private PaintView paintView;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_line_l_hw, container, false);
paintView = v.findViewById(R.id.lineLPaintView);
//here's where I try for fragment 2
if (savedInstanceState != null) {
if (savedInstanceState.containsKey("line test")) {
paintView.setPaths(savedInstanceState.<FingerPath>getParcelableArrayList("line
test"));
}
}
DisplayMetrics metrics = new DisplayMetrics();
getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
paintView.init(metrics);
setHasOptionsMenu(true);
return v;
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.main, menu);
super.onCreateOptionsMenu(menu, inflater);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.normal:
paintView.normal();
return true;
case R.id.clear:
paintView.clear();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList("line test", paintView.getPaths());
}
}
PaintView.java,控制绘图
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BlurMaskFilter;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.EmbossMaskFilter;
import android.graphics.MaskFilter;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import java.util.ArrayList;
public class PaintView extends View {
public static int BRUSH_SIZE = 10;
public static final int DEFAULT_COLOR = Color.WHITE;
public static int DEFAULT_BG_COLOR = Color.GRAY;
private static final float TOUCH_TOLERANCE = 4;
private float mX, mY;
private Path mPath;
private Paint mPaint;
private static ArrayList<FingerPath> paths = new ArrayList<>();
private int currentColor;
private int backgroundColor = DEFAULT_BG_COLOR;
private int strokeWidth;
private boolean emboss;
private boolean blur;
private MaskFilter mEmboss;
private MaskFilter mBlur;
private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);
public PaintView(Context context) {
this(context, null);
}
public PaintView(Context context, AttributeSet attrs) {
super(context, attrs);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(DEFAULT_COLOR);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setXfermode(null);
mPaint.setAlpha(0xff);
mEmboss = new EmbossMaskFilter(new float[] {1, 1, 1}, 0.4f, 6, 3.5f);
mBlur = new BlurMaskFilter(5, BlurMaskFilter.Blur.NORMAL);
}
public ArrayList getPaths() {
return paths;
}
public ArrayList setPaths(ArrayList<FingerPath> list) {
return this.paths = list;
}
public Path getMPath() {
return mPath;
}
public void init(DisplayMetrics metrics) {
int height = metrics.heightPixels;
int width = metrics.widthPixels;
mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
currentColor = DEFAULT_COLOR;
strokeWidth = BRUSH_SIZE;
}
public void normal() {
emboss = false;
blur = false;
}
public void clear() {
backgroundColor = DEFAULT_BG_COLOR;
paths.clear();
normal();
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
canvas.save();
mCanvas.drawColor(backgroundColor);
for (FingerPath fp: paths) {
mPaint.setColor(fp.color);
mPaint.setStrokeWidth(fp.strokeWidth);
mPaint.setMaskFilter(null);
if (fp.emboss)
mPaint.setMaskFilter(mEmboss);
else if (fp.blur)
mPaint.setMaskFilter(mBlur);
mCanvas.drawPath(fp.path, mPaint);
}
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.restore();
}
private void touchStart(float x, float y) {
mPath = new Path();
FingerPath fp = new FingerPath(currentColor, emboss, blur, strokeWidth, mPath);
paths.add(fp);
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touchMove(float x, float y) {
float dx = Math.abs(x-mX);
float dy = Math.abs(y-mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}
private void touchUp() {
mPath.lineTo(mX, mY);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN :
touchStart(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE :
touchMove(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP :
touchUp();
invalidate();
break;
}
return true;
}
}
FingerPath.java,包含 Parcelable 接口
import android.graphics.Path;
import android.os.Parcel;
import android.os.Parcelable;
public class FingerPath implements Parcelable {
public int color;
public boolean emboss;
public boolean blur;
public int strokeWidth;
public Path path;
public FingerPath(int color, boolean emboss, boolean blur, int strokeWidth, Path path) {
this.color = color;
this.emboss = emboss;
this.blur = blur;
this.strokeWidth = strokeWidth;
this.path = path;
}
protected FingerPath(Parcel in) {
color = in.readInt();
emboss = in.readByte() != 0;
blur = in.readByte() != 0;
strokeWidth = in.readInt();
}
public static final Creator<FingerPath> CREATOR = new Creator<FingerPath>() {
@Override
public FingerPath createFromParcel(Parcel in) {
return new FingerPath(in);
}
@Override
public FingerPath[] newArray(int size) {
return new FingerPath[size];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeInt(color);
parcel.writeByte((byte) (emboss ? 1 : 0));
parcel.writeByte((byte) (blur ? 1 : 0));
parcel.writeInt(strokeWidth);
}
}
解决方案
推荐阅读
- rest - Stripe API 请求与 Postman 一起使用,但 Apex Rest Callout 失败
- reactjs - 我应该如何在 React JS 中使用函数的变量作为道具
- javascript - 在nodejs后端读取音频持续时间
- javascript - 无法使用反应测试库测试包含 SVG 的组件
- reactjs - 动态 SVG 导入不使用 Typescript 显示图像
- c - 将浮点数转换为 uint 的最简洁方法
- c# - 将 json 反序列化为字典
在 C# 应用程序中 - javascript - HTML 选项卡内容作为绘图对象
- python-3.x - Python dict + RuntimeError:尝试反序列化 CUDA 设备上的对象
- r - 在base R中的一个图中使用相同的变量绘制两个箱线图