Android Lesson 3: work with ImageView

phptuts December 25, 2015

After creating a new project, we see the directories of resources:

Step 1: To use ImageView, we create a new image resource, copy an image in your computer like:

and paste it in res/drawable/

Note: a resource name must begin with a character

Step 2: open file res/layout/contain_main.xml.
Now we can put some codes in this file to make some examples

Ex 1:

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/imgview"
        android:src="@drawable/logo"
        />

The image will keep size like the figure:

Ex 2:

        <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/imgview"
        android:src="@drawable/logo"
        />

Ex 3:

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/imgview"
        android:src="@drawable/logo"
        />

Work with ImageView.ScaleType

ImageView.ScaleType has 8 options:

CENTER	Center the image in the view, but perform no scaling.
CENTER_CROP	Scale the image uniformly (maintain the image’s aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding).
CENTER_INSIDE	Scale the image uniformly (maintain the image’s aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding).
FIT_CENTER	Compute a scale that will maintain the original src aspect ratio, but will also ensure that src fits entirely inside dst. At least one axis (X or Y) will fit exactly. The result is centered inside dst.
FIT_END	Compute a scale that will maintain the original src aspect ratio, but will also ensure that src fits entirely inside dst. At least one axis (X or Y) will fit exactly. END aligns the result to the right and bottom edges of dst.
FIT_START	Compute a scale that will maintain the original src aspect ratio, but will also ensure that src fits entirely inside dst. At least one axis (X or Y) will fit exactly. START aligns the result to the left and top edges of dst.
FIT_XY	Scale in X and Y independently, so that src matches dst exactly. This may change the aspect ratio of the src.
MATRIX	Scale using the image matrix when drawing.

Ex scaleType 1: with value: center

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/imgview"
        android:src="@drawable/logo"
        android:scaleType="center"
        />