Resizing ImageView to fit to aspect ratio

问题

I need to resize an ImageView such that it fits to the screen, maintains the same aspect ratio. The following conditions hold:

• Images are a fixed width (size of the width of screen)
• Images are downloaded from the Internet, i.e. size can only be determined later
• Aspect ratio for each image will vary; some are tall, some are square, some are flat
• ImageView\'s height needs to change, either bigger or smaller based on the aspect ratio of the
• Excess height is cropped, can\'t have a lot of empty space like it is by default.

For example, a tiny 50x50 image on a 400 px width screen would scale the image up to 400x400 px. A 800x200 image would scale to 400x100.

I\'ve looked at most of the other threads, and many proposed solutions like simply changing adjustViewBounds and scaleType will only scale down an image, and not scale it up.

回答1:

I created it with the help of this Bob Lee's answer in this post: Android: How to stretch an image to the screen width while maintaining aspect ratio?

package com.yourpackage.widgets;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;

public class AspectRatioImageView extends ImageView {

    public AspectRatioImageView(Context context) {
        super(context);
    }

    public AspectRatioImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public AspectRatioImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int width = MeasureSpec.getSize(widthMeasureSpec);
        int height = width * getDrawable().getIntrinsicHeight() / getDrawable().getIntrinsicWidth();
        setMeasuredDimension(width, height);
    }
}

Now to use it in the XML:

<com.yourpackage.widgets.AspectRatioImageView android:layout_centerHorizontal="true"
    android:src="@drawable/yourdrawable" android:id="@+id/image"
    android:layout_alignParentTop="true" android:layout_height="wrap_content"
    android:layout_width="match_parent" android:adjustViewBounds="true" />

Have fun!

回答2:

ImageView mImageView; // This is the ImageView to change

// Use this in onWindowFocusChanged so that the ImageView is fully loaded, or the dimensions will end up 0.
public void onWindowFocusChanged(boolean hasFocus) 
{
    super.onWindowFocusChanged(hasFocus);

    // Abstracting out the process where you get the image from the internet
    Bitmap loadedImage = getImageFromInternet (url);

    // Gets the width you want it to be
    intendedWidth = mImageView.getWidth();

    // Gets the downloaded image dimensions
    int originalWidth = loadedImage.getWidth();
    int originalHeight = loadedImage.getHeight();

    // Calculates the new dimensions
    float scale = (float) intendedWidth / originalWidth;
    int newHeight = (int) Math.round(originalHeight * scale);

    // Resizes mImageView. Change "FrameLayout" to whatever layout mImageView is located in.
    mImageView.setLayoutParams(new FrameLayout.LayoutParams(
            FrameLayout.LayoutParams.WRAP_CONTENT,
            FrameLayout.LayoutParams.WRAP_CONTENT));
    mImageView.getLayoutParams().width = intendedWidth;
    mImageView.getLayoutParams().height = newHeight;
}

回答3:

I prefer Agarwal's answer with some modifications, because it is resuable:

package com.yourpackage.widgets;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.AppCompatImageView;
import android.util.AttributeSet;
import android.view.ViewGroup;

public class AspectRatioImageView extends AppCompatImageView {

    public AspectRatioImageView(Context context) 
    {       
        super(context);
        this.setScaleType(ScaleType.FIT_XY);
    }

    public AspectRatioImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.setScaleType(ScaleType.FIT_XY);
    }

    public AspectRatioImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.setScaleType(ScaleType.FIT_XY);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
    {
        Drawable d = getDrawable();

        if (d != null && d.getIntrinsicHeight() > 0)
        {
            int width = getLayoutParams().width;
            int height = getLayoutParams().height;

            // تو این حالت مبنای محاسبات رو بر اساس طول در نظر می گیرم
            if (height == ViewGroup.LayoutParams.WRAP_CONTENT || (width > 0 &&  width < 10000))
            {
                if (width <= 0);
                width = MeasureSpec.getSize(widthMeasureSpec);

                if (width > 0)
                    height = width * d.getIntrinsicHeight() / d.getIntrinsicWidth();

                // ارتفاع نباید از بیشینه ارتفاع بیشتر باشه
                if (height > getMaxHeight()) {
                    height = getMaxHeight();
                    width = height * d.getIntrinsicWidth() / d.getIntrinsicHeight();
                }

            }
            else if (width == ViewGroup.LayoutParams.WRAP_CONTENT  || (height > 0 &&  height < 10000))
            {
                // اگر مقداری برای ارتفاع مشخص نشده بود ارتفاع پدر رو در نظر می گیریم
                if (height <= 0)
                    height = MeasureSpec.getSize(heightMeasureSpec);

                // اگه ارتفاع مشخص بود که می تونیم طول رو بر اساسش حساب کنیم
                if (height > 0)
                    width = height * d.getIntrinsicWidth() / d.getIntrinsicHeight();

                // طول نباید از بیشینه طول بیشتر باشه
                if (width > getMaxWidth()) {
                    width = getMaxWidth();
                    height = width * d.getIntrinsicHeight() / d.getIntrinsicWidth();
                }
            }

            // اگه محاسبات موفقیت آمیز بود
            if (width > 0 && height > 0)
                setMeasuredDimension(width, height);
                // در غیر اینصورت همه چی رو می سپریم به خود ایمیج ویو
            else
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
        else
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

Now to use it in the XML:

<com.yourpackage.widgets.AspectRatioImageView 
android:src="@drawable/yourdrawable"
android:layout_height="wrap_content"
android:layout_width="match_parent"/>

来源：https://stackoverflow.com/questions/12400113/resizing-imageview-to-fit-to-aspect-ratio