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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.tools.lint.checks;
import static com.android.SdkConstants.ANDROID_URI;
import static com.android.SdkConstants.ATTR_BACKGROUND;
import static com.android.SdkConstants.ATTR_FOREGROUND;
import static com.android.SdkConstants.ATTR_LAYOUT;
import static com.android.SdkConstants.ATTR_LAYOUT_GRAVITY;
import static com.android.SdkConstants.FRAME_LAYOUT;
import static com.android.SdkConstants.LAYOUT_RESOURCE_PREFIX;
import static com.android.SdkConstants.VIEW_INCLUDE;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.resources.ResourceType;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Context;
import com.android.tools.lint.detector.api.Detector.JavaPsiScanner;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.JavaContext;
import com.android.tools.lint.detector.api.LayoutDetector;
import com.android.tools.lint.detector.api.LintUtils;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.Location.Handle;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.XmlContext;
import com.android.utils.Pair;
import com.intellij.psi.JavaElementVisitor;
import com.intellij.psi.PsiExpression;
import com.intellij.psi.PsiMethod;
import com.intellij.psi.PsiMethodCallExpression;
import com.intellij.psi.PsiReferenceExpression;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* Checks whether a root FrameLayout can be replaced with a {@code } tag.
*/
public class MergeRootFrameLayoutDetector extends LayoutDetector implements JavaPsiScanner {
/**
* Set of layouts that we want to enable the warning for. We only warn for
* {@code }'s that are the root of a layout included from
* another layout, or directly referenced via a {@code setContentView} call.
*/
private Set mWhitelistedLayouts;
/**
* Set of pending [layout, location] pairs where the given layout is a
* FrameLayout that perhaps should be replaced by a {@code } tag (if
* the layout is included or set as the content view. This must be processed
* after the whole project has been scanned since the set of includes etc
* can be encountered after the included layout.
*/
private List> mPending;
/** The main issue discovered by this detector */
public static final Issue ISSUE = Issue.create(
"MergeRootFrame", //$NON-NLS-1$
"FrameLayout can be replaced with `` tag",
"If a `` is the root of a layout and does not provide background " +
"or padding etc, it can often be replaced with a `` tag which is slightly " +
"more efficient. Note that this depends on context, so make sure you understand " +
"how the `` tag works before proceeding.",
Category.PERFORMANCE,
4,
Severity.WARNING,
new Implementation(
MergeRootFrameLayoutDetector.class,
EnumSet.of(Scope.ALL_RESOURCE_FILES, Scope.JAVA_FILE)))
.addMoreInfo(
"http://android-developers.blogspot.com/2009/03/android-layout-tricks-3-optimize-by.html"); //$NON-NLS-1$
/** Constructs a new {@link MergeRootFrameLayoutDetector} */
public MergeRootFrameLayoutDetector() {
}
@Override
public void afterCheckProject(@NonNull Context context) {
if (mPending != null && mWhitelistedLayouts != null) {
// Process all the root FrameLayouts that are eligible, and generate
// suggestions for replacements for any layouts that are included
// from other layouts
for (Pair pair : mPending) {
String layout = pair.getFirst();
if (mWhitelistedLayouts.contains(layout)) {
Handle handle = pair.getSecond();
Object clientData = handle.getClientData();
if (clientData instanceof Node) {
if (context.getDriver().isSuppressed(null, ISSUE, (Node) clientData)) {
return;
}
}
Location location = handle.resolve();
context.report(ISSUE, location,
"This `` can be replaced with a `` tag");
}
}
}
}
// Implements XmlScanner
@Override
public Collection getApplicableElements() {
return Arrays.asList(VIEW_INCLUDE, FRAME_LAYOUT);
}
@Override
public void visitElement(@NonNull XmlContext context, @NonNull Element element) {
String tag = element.getTagName();
if (tag.equals(VIEW_INCLUDE)) {
String layout = element.getAttribute(ATTR_LAYOUT); // NOTE: Not in android: namespace
if (layout.startsWith(LAYOUT_RESOURCE_PREFIX)) { // Ignore @android:layout/ layouts
layout = layout.substring(LAYOUT_RESOURCE_PREFIX.length());
whiteListLayout(layout);
}
} else {
assert tag.equals(FRAME_LAYOUT);
if (LintUtils.isRootElement(element) &&
((isWidthFillParent(element) && isHeightFillParent(element)) ||
!element.hasAttributeNS(ANDROID_URI, ATTR_LAYOUT_GRAVITY))
&& !element.hasAttributeNS(ANDROID_URI, ATTR_BACKGROUND)
&& !element.hasAttributeNS(ANDROID_URI, ATTR_FOREGROUND)
&& !hasPadding(element)) {
String layout = LintUtils.getLayoutName(context.file);
Handle handle = context.createLocationHandle(element);
handle.setClientData(element);
if (!context.getProject().getReportIssues()) {
// If this is a library project not being analyzed, ignore it
return;
}
if (mPending == null) {
mPending = new ArrayList>();
}
mPending.add(Pair.of(layout, handle));
}
}
}
private void whiteListLayout(String layout) {
if (mWhitelistedLayouts == null) {
mWhitelistedLayouts = new HashSet();
}
mWhitelistedLayouts.add(layout);
}
// Implements JavaScanner
@Override
public List getApplicableMethodNames() {
return Collections.singletonList("setContentView"); //$NON-NLS-1$
}
@Override
public void visitMethod(@NonNull JavaContext context, @Nullable JavaElementVisitor visitor,
@NonNull PsiMethodCallExpression call, @NonNull PsiMethod method) {
PsiExpression[] expressions = call.getArgumentList().getExpressions();
if (expressions.length == 1 && expressions[0] instanceof PsiReferenceExpression) {
PsiReferenceExpression expression = (PsiReferenceExpression)expressions[0];
if (expression.getQualifier() instanceof PsiReferenceExpression) {
PsiReferenceExpression inner = (PsiReferenceExpression)expression.getQualifier();
if (ResourceType.LAYOUT.getName().equals(inner.getReferenceName())) {
String layoutName = expression.getReferenceName();
if (layoutName != null) {
whiteListLayout(layoutName);
}
}
}
}
}
}
