# Android Lesson 3: work with ImageView

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"
/>

Ex scaleType 2: with value: centerCrop

Ex scaleType 3: with value: fitStart