Add multi-density vector graphics

Android Studio includes a tool called Vector Asset Studio that helps you add material icons and import Scalable Vector Graphic (SVG) and Adobe Photoshop Document (PSD) files into your project as vector drawable resources. Using vector drawables instead of bitmaps reduces the size of your APK because the same file can be resized for different screen densities without loss of image quality. For older versions of Android that don't support vector drawables, Vector Asset Studio can, at build time, turn your vector drawables into different bitmap sizes for each screen density.

About Vector Asset Studio

Vector Asset Studio adds a vector graphic to the project as an XML file that describes the image. Maintaining one XML file can be easier than updating multiple raster graphics at various resolutions.

Android 4.4 (API level 20) and lower doesn't support vector drawables. If your minimum API level is set at one of these API levels, you have two options when using Vector Asset Studio: generate Portable Network Graphic (PNG) files (the default) or use the Support Library.

For backward-compatibility, Vector Asset Studio generates raster images of the vector drawable. The vector and raster drawables are packaged together in the APK. You can refer to vector drawables as Drawable in Java code or @drawable in XML code; when your app runs, the corresponding vector or raster image displays automatically depending on the API level.

If you want to use vector drawables only, you can use Android Support Library 23.2 or higher. This technique requires a change to your build.gradle file before you run Vector Asset Studio, as described in Support Library Backward Compatibility. The VectorDrawableCompat class in the Support Library allows you to support VectorDrawable in Android 2.1 (API level 7) and higher.

Supported vector graphic types

The Google Material Design specification provides material icons that you can use in your Android apps. Vector Asset Studio helps you choose, import, and size material icons, as well as define opacity and the Right-to-Left (RTL) mirroring setting.

Vector Asset Studio also lets you import your own SVG and PSD files. SVG is an XML-based open standard of the World Wide Web Consortium (W3C). The PSD file format supports Adobe Photoshop features. Vector Asset Studio supports the essential standards, but not all SVG and PSD features. When you specify an SVG or PSD file, Vector Asset Studio gives immediate feedback about whether the graphics code is supported or not. It converts the file into an XML file containing VectorDrawable code. If you receive errors, you should verify that your vector drawable appears as intended. For more information about allowed PSD features, see Support and restrictions for PSD files.

For Android 5.0 (API level 21) and higher, you can use the AnimatedVectorDrawable class to animate the properties of the VectorDrawable class. With the Support Library, you can use the AnimatedVectorDrawableCompat class to animate the VectorDrawable class for Android 3.0 (API level 11) and higher. For more information, see Animate vector drawables.

Considerations for SVG and PSD files

A vector drawable is appropriate for simple icons. The material icons provide good examples of the types of images that work well as vector drawables in an app. In contrast, many app launch icons do have many details, so they work better as raster images.

The initial loading of a vector drawable can cost more CPU cycles than the corresponding raster image. Afterward, memory use and performance are similar between the two. We recommend that you limit a vector image to a maximum of 200 x 200 dp; otherwise, it can take too long to draw.

Although vector drawables do support one or more colors, in many cases it makes sense to color icons black (android:fillColor="#FF000000"). Using this approach, you can add a tint to the vector drawable that you placed in a layout, and the icon color changes to the tint color. If the icon color isn't black, the icon color might instead blend with the tint color.

Vector drawable backward-compatibility solutions

The following table summarizes the two techniques that you can use for backward-compatibility:

Using vector drawables can produce a smaller APK, but the initial loading of vector drawables can take longer.

PNG generation

Android 5.0 (API level 21) and higher provides vector drawable support. If your app has a minimum API level that's lower, Vector Asset Studio adds the vector drawable file to your project; also, at build time, Gradle creates PNG raster images at various resolutions. Gradle generates the PNG densities specified by the Domain Specific Language (DSL) generatedDensities property in a build.gradle file.

For Android 5.0 (API level 21) and higher, Vector Asset Studio supports all of the VectorDrawable elements. For backward compatibility with Android 4.4 (API level 20) and lower, Vector Asset Studio supports the following XML elements:

You can change the XML code that Vector Asset Studio generates, although it’s not a best practice. Changing the values in the code should not cause any issues, as long as they’re valid and static. If you want to add XML elements, you need to make sure that they’re supported based on your minimum API level.

Support Library

This technique requires Android Support Library 23.2 or higher and Android Plugin for Gradle 2.0 or higher, and uses vector drawables only. The VectorDrawableCompat class in the Support Library allows you to support VectorDrawable in Android 2.1 (API level 7) and higher.

Before using Vector Asset Studio, you must add a statement to your build.gradle file:

android {
    defaultConfig {
        vectorDrawables.useSupportLibrary = true
    }
}

dependencies {
    implementation 'com.android.support:appcompat-v7:23.2.0'
}

android {
    defaultConfig {
        vectorDrawables.useSupportLibrary = true
    }
}

dependencies {
    implementation("com.android.support:appcompat-v7:23.2.0")
}

You must also use coding techniques that are compatible with the Support Library, such as using the app:srcCompat attribute instead of the android:src attribute for vector drawables. For more information, see Android Support Library 23.2.

Running Vector Asset Studio

To start Vector Asset Studio:

1. In Android Studio, open an Android app project.
2. In the Project window, select the Android view.
3. Right-click the res folder and select New > Vector Asset.

Some other project views and folders have this menu item as well.

Vector Asset Studio appears.



Figure 1. Vector Asset Studio.

4. If a Need Newer Android Plugin for Gradle dialog appears instead, correct your Gradle version as follows:
1. Select File > Project Structure.
2. In the Project Structure dialog, select Project.
3. In the Android Plugin Version field, change the Android Plugin for Gradle version to 1.5.0 or higher, and click OK.

Gradle syncs the project.

4. In the Android view of the Project window, right-click the res folder and select New > Vector Asset.

Vector Asset Studio appears.

5. Continue with Importing a Vector Graphic.

Importing a vector graphic

Vector Asset Studio helps you to import a vector graphics file into your app project. Follow one of the following procedures:

• Adding a material icon
• Importing an SVG or PSD file

Adding a material icon

After you open Vector Asset Studio, you can add a material icon as follows:

1. In Vector Asset Studio, select Material Icon.
2. In the Icon field, click the button.

3. The Select Icon dialog appears. You can filter which icons are visible by selecting an icon category from the list on the left or typing in the search field as shown in figure 2.

   

   Figure 2. Filtering material icons in the Vector Asset Studio.

Select a material icon and click OK. The icon appears in the Vector Drawable Preview.

4. Optionally change the resource name, size, opacity, and Right-To-Left (RTL) mirroring setting:
   • Name - Type a new name if you don’t want to use the default name. Vector Asset Studio automatically creates a unique name (adds a number to the end of the name) if that resource name already exists in the project. The name can contain lowercase characters, underscores, and digits only.
   • Override - Select this option if you want to adjust the size of the image. When you type a new size, the change appears in the preview area.

   The default is 24 x 24 dp, which is defined in the material design specification. Deselect the checkbox to return to the default.

   • Opacity - Use the slider to adjust the opacity of the image. The change appears in the preview area.
   • Enable auto mirroring for RTL layout - Select this option if you want a mirror image to display when the layout is right to left, instead of left to right. For example, some languages are read right to left; if you have an arrow icon, you might want to display a mirror image of it in this case. Note that if you’re working with an older project, you might also need to add android:supportsRtl="true" to your app manifest. Auto-mirroring is supported on Android 5.0 (API level 21) and higher, and with the Support Library.
5. Click Next.
6. Optionally change the module and resource directory:
• Res Directory - Select the resource source set where you want to add the vector drawable: src/main/res, src/debug/res, src/release/res, or a user-defined source set. The main source set applies to all build variants, including debug and release. The debug and release source sets override the main source set and apply to one version of a build. The debug source set is for debugging only. To define a new source set, select File > Project Structure > app > Build Types. For example, you could define a beta source set and create a version of an icon that includes the text "BETA" in the bottom right corner. For more information, see Configure Build Variants.

The Output Directories area displays the vector drawable and the directory where it will appear.

7. Click Finish.

Vector Asset Studio adds an XML file defining the vector drawable to the project in the app/src/main/res/drawable/ folder. From the Android view of the Project window, you can view the generated vector XML file in the drawable folder.

8. Build the project.

If the minimum API level is Android 4.4 (API level 20) and lower, and you haven't enabled the Support Library technique, Vector Asset Studio generates PNG files. From the Project Files view of the Project window, you can view the generated PNG and XML files in the app/build/generated/res/pngs/debug/ folder.

You should not edit these generated raster files, but instead work with the vector XML file. The build system regenerates the raster files automatically when needed so you don’t need to maintain them.

Importing an SVG or PSD file

After you open Vector Asset Studio, you can import an SVG or PSD file as follows:

1. In Vector Asset Studio, select Local file.

The file must be on a local drive. If it’s located on the network, for example, you need to download it to a local drive first.

2. Specify an Image file by clicking … .

The image appears in the Vector Drawable Preview.

If the SVG or PSD file contains unsupported features, an error appears at the bottom of Vector Asset Studio, as shown in figure 3.



Figure 3. Vector Asset Studio displaying some errors.

If you see errors, you need to make sure that the imported vector drawable renders properly. Scroll through the list to view the errors.

For a list of supported elements, see Vector Drawable Backward-Compatibility Solutions. For more information about allowed PSD files, see Support and Restrictions for PSD Files.

3. Optionally change the resource name, size, opacity, and Right-To-Left (RTL) mirroring setting:
• Name - Type a new name if you don’t want to use the default name. Vector Asset Studio automatically creates a unique name (adds a number to the end of the name) if that resource name already exists in the project. The name can contain lowercase characters, underscores, and digits only.
• Override - Select this option if you want to adjust the size of the image. After you select it, the size changes to the size of the image itself. Whenever you change the size, the change appears in the preview area. The default is 24 x 24 dp, which is defined in the material design specification.
• Opacity - Use the slider to adjust the opacity of the image. The change appears in the preview area.
• Enable auto mirroring for RTL layout - Select this option if you want a mirror image to display when the layout is right to left, instead of left to right. For example, some languages are read right to left; if you have an arrow icon, you might want to display a mirror image of it in this case. Note that if you’re working with an older project, you might need to add android:supportsRtl="true" to your app manifest. Auto-mirroring is supported by Android 5.0 (API level 21) and higher, and the Support Library.
4. Click Next.
5. Optionally change the resource directory:
• Res Directory - Select the resource source set where you want to add the vector drawable: src/main/res, src/debug/res, src/release/res, or a user-defined source set. The main source set applies to all build variants, including debug and release. The debug and release source sets override the main source set and apply to one version of a build. The debug source set is for debugging only. To define a new source set, select File > Project Structure > app > Build Types. For example, you could define a beta source set and create a version of an icon that includes the text "BETA" in the bottom right corner. For more information, see Configure Build Variants.

The Output Directories area displays the vector drawable and the directory where it will appear.

6. Click Finish.

Vector Asset Studio adds an XML file defining the vector drawable to the project in the app/src/main/res/drawable/ folder. From the Android view of the Project window, you can view the generated vector XML file in the drawable folder.

7. Build the project.

If the minimum API level is Android 4.4 (API level 20) and lower, and you haven't enabled the Support Library technique, Vector Asset Studio generates PNG files. From the Project Files view of the Project window, you can view the generated PNG and XML files in the app/build/generated/res/pngs/debug/ folder.

You should not edit these generated raster files, but instead work with the vector XML file. The build system regenerates the raster files automatically when needed so you don’t need to maintain them.

Adding a vector drawable to a layout

In a layout file, you can set any icon-related widget, such as ImageButton, ImageView, and so on, to point to a vector drawable. For example, the following layout shows a vector drawable displayed on a button:

Figure 4. A vector drawable displayed on a button in a layout.

To display a vector drawable on a widget, as shown in the figure:

1. Open a project and import a vector drawable.

This example uses a Phone/Tablet project generated with the New Project Wizard.

2. In the Android view of the Project window, double-click a layout XML file, such as content_main.xml.
3. Click the Design tab to display the Layout Editor.
4. Drag the ImageButton widget from the Palette window onto the Layout Editor.
5. In the Resources dialog, select Drawable in the left pane, and then select the vector drawable you imported. Click OK.

The vector drawable appears on the ImageButton in the layout.

6. To change the color of the image to the accent color defined in the theme, in the Properties window, locate the tint property and click … .
7. In the Resources dialog, select Color in the left pane, and then select colorAccent. Click OK.

The color of the image changes to the accent color in the layout.

If the project uses the Support Library, the ImageButton code should be similar to the following:

<ImageButton
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  app:srcCompat="@drawable/ic_build_black_24dp"
  tools:layout_editor_absoluteX="11dp"
  tools:layout_editor_absoluteY="225dp"
  android:id="@+id/imageButton"
  android:tint="@color/colorAccent" />

If the project doesn't use the Support Library, the vector drawable code would instead be android:src="@drawable/ic_build_black_24dp".

Referring to a vector drawable in code

You can normally refer to a vector drawable resource in a generic way in your code, and when your app runs, the corresponding vector or raster image displays automatically depending on the API level:

• In most cases, you can refer to vector drawables as @drawable in XML code or Drawable in Java code.

For example, the following layout XML code applies the image to a view:

<ImageView
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:src="@drawable/myimage" />

The following Java code retrieves the image as a Drawable:

Kotlin

val drawable = resources.getDrawable(R.drawable.myimage, theme)

Java

Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.myimage, getTheme());

The getResources() method resides in the Context class, which applies to UI objects, such as activities, fragments, layouts, views, and so on.

• If your app uses the Support Library at all (even if you don't have a vectorDrawables.useSupportLibrary = true statement in your build.gradle file), you can also refer to a vector drawable with an app:srcCompat statement. For example:

<ImageView
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    app:srcCompat="@drawable/myimage" />

• Occasionally, you might need to typecast the drawable resource to its exact class, such as when you need to use specific features of the VectorDrawable class. To do so, you could use Java code such as the following:

Kotlin

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    val vectorDrawable = drawable as VectorDrawable
} else {
    val bitmapDrawable = drawable as BitmapDrawable
}

Java

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
   VectorDrawable vectorDrawable = (VectorDrawable) drawable;
} else {
   BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
}

You can access vector drawable resources from the main thread only.

For the Support Library technique, you must use coding techniques that are compatible with the Support Library. For more information, see Android Support Library 23.2.

Modifying XML code generated by Vector Asset Studio

You can modify the vector drawable XML code, but not the PNGs and corresponding XML code generated at build time. However, we don't recommend it.

When using the PNG generation technique, Vector Asset Studio makes sure that the vector drawable and the PNGs match, and that the manifest contains the proper code. If you add code that's not supported on Android 4.4 (API level 20) and lower, your vector and PNG images might differ. You also need to make sure that the manifest contains the code to support your changes.

To modify the vector XML file when you're not using the Support Library technique:

1. In the Project window, double-click the generated vector XML file in the drawable folder.

The XML file appears in the editor and Preview windows.



Figure 5. A vector XML file displayed in the Code Editor and the Preview window.

2. Edit the XML code based on what’s supported by the minimum API level:
• Android 5.0 (API level 21) and higher - Vector Asset Studio supports all of the Drawable and VectorDrawable elements. You can add XML elements and change values.
• Android 4.4 (API level 20) and lower - Vector Asset Studio supports all of the Drawable elements and a subset of the VectorDrawable elements. See Vector Drawable Backward-Compatibility Solutions for a list. You can change values in the generated code and add XML elements that are supported.
3. Build the project and check that the vector drawable and corresponding raster images look the same.

Remember that the generated PNGs could display differently in the Preview window than in the app due to different rendering engines and any changes made to the vector drawable before a build. If you add code to the vector XML file created by Vector Asset Studio, any features unsupported in Android 4.4 (API level 20) and lower don't appear in the generated PNG files. As a result, when you add code, you should always check that the generated PNGs match the vector drawable. To do so, you could double-click the PNG in the Project Files view of the Project window; the left margin of the Code Editor also displays the PNG image when your code refers to the drawable, as shown in figure 6.



Figure 6. A PNG image displayed in the left margin of the Code Editor.

Deleting a vector drawable from a project

To remove a vector drawable from a project:

1. In the Project window, delete the generated vector XML file by selecting the file and pressing the Delete key (or select Edit > Delete).

The Safe Delete dialog appears.

2. Optionally select options to find where the file is used in the project, and click OK.

Android Studio deletes the file from the project and the drive. However, if you chose to search for places in the project where the file is used and some usages are found, you can view them and decide whether to delete the file.

3. Select Build > Clean Project.

Any auto-generated PNG and XML files corresponding to the deleted vector drawable are removed from the project and the drive.

Delivering an app Containing vector drawables

If you used the Support Library technique or your minimum API level is Android 5.0 (API level 21) or higher, your APK will contain the vector drawables that you added with Vector Asset Studio. These APKs will be smaller than if the vector images were converted to PNGs.

When your minimum API level includes Android 4.4 (API level 20) or lower, and you have corresponding vector drawables and raster images in your project, you have two options for delivering your APK files:

• Create one APK that includes both the vector drawables and the corresponding raster representations. This solution is the simplest to implement.
• Create separate APKs for different API levels. When you don’t include the corresponding raster images in the APK for Android 5.0 (API level 21) and higher, the APK can be much smaller in size. For more information, see Multiple APK Support.

Support and restrictions for PSD files

Vector Asset Studio doesn't support all PSD file features. The following list summarizes supported and unsupported PSD characteristics, as well as some conversion details.

Document

Supported:

• A PSD color mode of bitmap, grayscale, indexed, RGB, Lab, or CMYK.
• A color depth of 8, 16, or 32 bits.

Conversion details:

• PSD document dimensions become the vector drawable and viewport dimensions.

Not supported:

• A PSD color mode of duotone or multichannel.

Shapes

Supported:

• Clipping masks, if the clipping base is another shape.
• Shape operations, including merge/add, intersect, subtract, and exclude.

Not supported:

• Even-odd fill rule used by Photoshop shapes. In Android 6.0 (API level 23) and lower, vector drawables support the nonzero fill rule only. In self-intersecting shapes, this limitation can lead to rendering differences between the PSD and the resulting vector drawable. To fix this issue, add android:fillType="evenOdd" on the shape in the vector drawable. For example:

  <vector xmlns:android="https://schemas.android.com/apk/res/android"
      android:viewportHeight="168"
      android:height="24dp"
      android:viewportWidth="209"
      android:width="24dp">
  
      <path
          android:fillAlpha="1.0"
          android:fillColor="#000000"
          android:fillType="evenOdd"
          android:pathData="M24,58 L24,167 L114,167 L114,66 M64,1 L64,96 L208,96 L208,8 M1,97 L146,139 L172,47"/>
  </vector>

Strokes and fills

Supported:

• Strokes, including color, opacity, width, join, cap, dashes, and alignment.
• Solid color fills and strokes.
• Stroke and fill colors specified as RGB, Lab, or CMYK.

Conversion details:

• If a stroke is dashed, clipped using a clipping base, or uses an alignment different from center, Vector Asset Studio converts it into a fill shape in the vector drawable.

Not supported:

• Color fills and strokes other than solid, such as gradients.

Opacity

Supported:

• Shape layers with an opacity of 0.

Conversion details:

• Vector Asset Studio multiplies the fill opacity with the layer opacity to compute the fill alpha.
• The tool multiplies the opacity of the clipping base (if there is a clipping base) with the fill alpha to compute the final fill alpha.
• The tool multiplies the stroke opacity with the layer opacity to compute the stroke alpha.
• The tool multiplies the opacity of the clipping base (if there is a clipping base) with the stroke alpha to compute the final stroke alpha.

Layers

Supported:

• Any visible shape layer.

Conversion details:

• Vector Asset Studio preserves the name of the layers in the vector drawable file.

Not supported:

• Layer effects.
• Adjustment and text layers.
• Blending modes (ignored).

Support and restrictions for SVG files

Vector Asset Studio doesn't support all SVG file features. The following section summarizes supported and unsupported features when the tool converts an SVG file to a VectorDrawable, along with additional conversion details.

Supported features

VectorDrawable supports all features from Tiny SVG 1.2 except for text.

Shapes

VectorDrawable supports SVG paths.

The tool converts primitive shapes such as circles, squares, and polygons to paths.

Transformations

The tool supports transformation matrices and applies them directly to child paths.

Groups

The tool supports group elements for translation, scaling, and rotation. Groups do not support an opacity property.

The tool also applies any group styling or opacity to child paths.

Fills and strokes

Paths can be filled and stroked using solid colors or gradients (linear, radial, or angular). Only centered strokes are supported. Blend modes are not supported. Dashed paths are not supported.

Masks

The tool supports one clipping mask per group.

Features not supported by the SVG importer

Any feature not listed in the Supported features section above is unsupported. Notable unsupported features include the following:

• Filter effects: effects such as drop shadows, blurs, and color matrix are not supported.
• Text: conversion of text to shapes using other tools is recommended.
• Pattern fills