| /* |
| * Copyright (C) 2016 - 2018 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 com.android.SdkConstants.ATTR_CONSTRAINT_LAYOUT_DESCRIPTION |
| import com.android.SdkConstants.ATTR_ID |
| import com.android.SdkConstants.ATTR_LAYOUT_HEIGHT |
| import com.android.SdkConstants.ATTR_LAYOUT_RESOURCE_PREFIX |
| import com.android.SdkConstants.ATTR_LAYOUT_WIDTH |
| import com.android.SdkConstants.AUTO_URI |
| import com.android.SdkConstants.CLASS_CONSTRAINT_LAYOUT_BARRIER |
| import com.android.SdkConstants.CLASS_CONSTRAINT_LAYOUT_FLOW |
| import com.android.SdkConstants.CLASS_CONSTRAINT_LAYOUT_GROUP |
| import com.android.SdkConstants.CLASS_CONSTRAINT_LAYOUT_GUIDELINE |
| import com.android.SdkConstants.CONSTRAINT_LAYOUT |
| import com.android.SdkConstants.MOTION_LAYOUT |
| import com.android.SdkConstants.TAG_INCLUDE |
| import com.android.SdkConstants.VALUE_MATCH_PARENT |
| import com.android.tools.lint.detector.api.Category |
| import com.android.tools.lint.detector.api.Implementation |
| import com.android.tools.lint.detector.api.Issue |
| import com.android.tools.lint.detector.api.LayoutDetector |
| 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.tools.lint.detector.api.isLayoutMarkerTag |
| import org.w3c.dom.Element |
| import org.w3c.dom.Node |
| |
| /** |
| * Check which looks for potential errors in declarations of |
| * ConstraintLayout, such as under specifying constraints. |
| */ |
| class ConstraintLayoutDetector : LayoutDetector() { |
| override fun getApplicableElements(): Collection<String> { |
| return setOf( |
| CONSTRAINT_LAYOUT.oldName(), |
| CONSTRAINT_LAYOUT.newName(), |
| MOTION_LAYOUT.oldName(), |
| MOTION_LAYOUT.newName() |
| ) |
| } |
| |
| override fun visitElement( |
| context: XmlContext, |
| element: Element |
| ) { |
| // In MotionLayouts you can specify the constraints elsewhere. |
| // Note that MotionLayoutDetector performs additional validation. |
| if (element.hasAttributeNS(AUTO_URI, ATTR_CONSTRAINT_LAYOUT_DESCRIPTION)) { |
| return |
| } |
| |
| // Views that are constrained by Flow do not require additional constraint. |
| var child = element.firstChild |
| // List of views that are Flow-constrained. |
| val flowList = ArrayList<String>() |
| while (child != null) { |
| if (child.nodeType != Node.ELEMENT_NODE) { |
| child = child.nextSibling |
| continue |
| } |
| |
| val elementTagName = (child as Element).tagName |
| if (CLASS_CONSTRAINT_LAYOUT_FLOW.isEquals(elementTagName)) { |
| val attributes = child.attributes |
| for (i in 0 until attributes.length) { |
| val attribute = attributes.item(i) |
| val name = attribute.localName ?: continue |
| val value = attribute.nodeValue |
| if (name.contains("constraint_referenced_ids")) { |
| flowList.addAll(value.split(",")) |
| } |
| } |
| } |
| child = child.nextSibling |
| } |
| |
| // Ensure that all the children have been constrained horizontally and vertically |
| child = element.firstChild |
| while (child != null) { |
| if (child.nodeType != Node.ELEMENT_NODE) { |
| child = child.nextSibling |
| continue |
| } |
| val layout = child as Element |
| val elementTagName = layout.tagName |
| if (CLASS_CONSTRAINT_LAYOUT_GUIDELINE.isEquals(elementTagName) || |
| // Groups do not need to be constrained |
| CLASS_CONSTRAINT_LAYOUT_GROUP.isEquals(elementTagName) || |
| // Don't flag includes; they might have the right constraints inside. |
| TAG_INCLUDE == elementTagName || |
| // <requestFocus/>, <tag/>, etc should not have constraint attributes |
| isLayoutMarkerTag(elementTagName) |
| ) { |
| child = child.getNextSibling() |
| continue |
| } else if (elementTagName.isNotBlank() && |
| CLASS_CONSTRAINT_LAYOUT_BARRIER.isEquals(elementTagName) && |
| scanForBarrierConstraint(layout) |
| ) { |
| // The Barrier has the necessary layout constraints. |
| // This element is constrained correctly. |
| break |
| } |
| var isConstrainedHorizontally = false |
| var isConstrainedVertically = false |
| val attributes = layout.attributes |
| for (i in 0 until attributes.length) { |
| val attribute = attributes.item(i) |
| val name = attribute.localName ?: continue |
| |
| // If the id is in the Flow, it's already constrained. |
| if (ATTR_ID == name) { |
| val value = attribute.nodeValue.split("/").last() |
| if (flowList.contains(value)) { |
| isConstrainedHorizontally = true |
| isConstrainedVertically = true |
| break |
| } |
| } |
| if (!name.startsWith(ATTR_LAYOUT_RESOURCE_PREFIX) || |
| name.endsWith("_creator") |
| ) { |
| continue |
| } |
| if (ATTR_LAYOUT_WIDTH == name && VALUE_MATCH_PARENT == attribute.nodeValue || |
| name.endsWith("toLeftOf") || |
| name.endsWith("toRightOf") || |
| name.endsWith("toStartOf") || |
| name.endsWith("toEndOf") || |
| name.endsWith("toCenterX") |
| ) { |
| isConstrainedHorizontally = true |
| if (isConstrainedVertically) { |
| break |
| } |
| } else if (ATTR_LAYOUT_HEIGHT == name && VALUE_MATCH_PARENT == attribute.nodeValue || |
| name.endsWith("toTopOf") || |
| name.endsWith("toBottomOf") || |
| name.endsWith("toCenterY") || |
| name.endsWith("toBaselineOf") |
| ) { |
| isConstrainedVertically = true |
| if (isConstrainedHorizontally) { |
| break |
| } |
| } |
| } |
| if (!isConstrainedHorizontally || !isConstrainedVertically) { |
| // Don't complain if the element doesn't specify absolute x/y - that's |
| // when it gets confusing |
| val message: String = when { |
| isConstrainedVertically -> |
| "This view is not constrained horizontally: at runtime it will jump to the left unless you add a horizontal constraint" |
| isConstrainedHorizontally -> |
| "This view is not constrained vertically: at runtime it will jump to the top unless you add a vertical constraint" |
| else -> |
| "This view is not constrained. It only has designtime positions, so it will jump to (0,0) at runtime unless you add the constraints" |
| } |
| context.report(ISSUE, layout, context.getNameLocation(layout), message) |
| } |
| child = child.getNextSibling() |
| } |
| } |
| |
| companion object { |
| @JvmField |
| val ISSUE = |
| Issue.create( |
| id = "MissingConstraints", |
| briefDescription = "Missing Constraints in ConstraintLayout", |
| explanation = """ |
| The layout editor allows you to place widgets anywhere on the canvas, \ |
| and it records the current position with designtime attributes (such as \ |
| `layout_editor_absoluteX`). These attributes are **not** applied at \ |
| runtime, so if you push your layout on a device, the widgets may appear \ |
| in a different location than shown in the editor. To fix this, make sure \ |
| a widget has both horizontal and vertical constraints by dragging from \ |
| the edge connections. |
| """, |
| category = Category.CORRECTNESS, |
| priority = 6, |
| severity = Severity.ERROR, |
| implementation = Implementation( |
| ConstraintLayoutDetector::class.java, |
| Scope.RESOURCE_FILE_SCOPE |
| ), |
| androidSpecific = true |
| ) |
| |
| /** |
| * @param element to scan |
| * @return true if barrier specific constraint is set. False |
| * otherwise. |
| */ |
| private fun scanForBarrierConstraint(element: Element): Boolean { |
| val attributes = element.attributes |
| for (i in 0 until attributes.length) { |
| val attribute = attributes.item(i) |
| val name = attribute.localName ?: continue |
| if (name.endsWith("barrierDirection")) { |
| return true |
| } |
| } |
| return false |
| } |
| } |
| } |
