我正在尝试在 VectorDrawable 上实现带有一些动画的简单 ViewPager。
正在关注this very good example使用点切换的漂亮标签滚动的解决方案。
唯一的区别是我使用的是矢量动画。作为一项 Activity ,它就像一个魅力,添加了 ViewPager,动画不始终启动。
compileSdkVersion 25
buildToolsVersion "26.0.2"
targetSdkVersion 25
我正在我的设备 (SG7) 上调试,我在 animation.start()
上设置了断点所有这些都在一个大的 VectorDrawable 上工作,其中有 3 个动画组。
2个字幕一开始就滑进去,然后无限滚动旋转,旋转一直有效。
Activity
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mHideHandler.post(mHidePart2Runnable);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabDots);
tabLayout.setupWithViewPager(mViewPager, true);
};
fragment :
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
静态 fragment
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_fullscreen, container, false);
View imgView = rootView.findViewById(R.id.vec_anim);
Drawable drawable = ((ImageView)imgView).getDrawable();
if (drawable instanceof Animatable) {
((Animatable) drawable).start();
};
return rootView;
}
我是这一切的新手,想描述 SVG 大小对性能的影响(考虑缓存 svgs 并在创建 View 时触发动画可能......)我正在尝试优化它并使其成为现实光滑的。但首先,它不能正常工作。
为什么换页时断点不总是命中?
有更好的方法吗?
最佳答案
试试这个,
Add library
compile com.mcxiaoke.viewpagerindicator:library:2.4.1@aar'.Your main layout file,
<RelativeLayout
android:id="@+id/pager_layout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="right">
<android.support.v4.view.ViewPager
android:id="@+id/pager_profile"
android:layout_width="fill_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
</android.support.v4.view.ViewPager>
<yourpackagename.utils.CirclePageIndicator
android:id="@+id/cover_photo_indicator"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:foregroundGravity="right"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:padding="10dip" />
</RelativeLayout>
- Create custom class
CirclePageIndicator
/**
* Draws circles (one for each view). The current view position is filled and
* others are only stroked.
*/
public class CirclePageIndicator extends View implements PageIndicator {
private static final int INVALID_POINTER = -1;
private float mRadius;
private final Paint mPaintPageFill = new Paint(ANTI_ALIAS_FLAG);
private final Paint mPaintStroke = new Paint(ANTI_ALIAS_FLAG);
private final Paint mPaintFill = new Paint(ANTI_ALIAS_FLAG);
private ViewPager mViewPager;
private ViewPager.OnPageChangeListener mListener;
private int mCurrentPage;
private int mSnapPage;
private float mPageOffset;
private int mScrollState;
private int mOrientation;
private boolean mCentered;
private boolean mSnap;
private int mTouchSlop;
private float mLastMotionX = -1;
private int mActivePointerId = INVALID_POINTER;
private boolean mIsDragging;
public CirclePageIndicator(Context context) {
this(context, null);
}
public CirclePageIndicator(Context context, AttributeSet attrs) {
this(context, attrs, R.attr.vpiCirclePageIndicatorStyle);
}
public CirclePageIndicator(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
if (isInEditMode()) return;
//Load defaults from resources
final Resources res = getResources();
final int defaultPageColor = res.getColor(R.color.default_circle_indicator_page_color);
//default_circle_indicator_fill_color
final int defaultFillColor = res.getColor(R.color.holo_blue_dark);
final int defaultOrientation = res.getInteger(R.integer.default_circle_indicator_orientation);
final int defaultStrokeColor = res.getColor(R.color.default_circle_indicator_stroke_color);
final float defaultStrokeWidth = res.getDimension(R.dimen.default_circle_indicator_stroke_width);
final float defaultRadius = res.getDimension(R.dimen.default_circle_indicator_radius);
final boolean defaultCentered = res.getBoolean(R.bool.default_circle_indicator_centered);
final boolean defaultSnap = res.getBoolean(R.bool.default_circle_indicator_snap);
//Retrieve styles attributes
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, 0);
mCentered = a.getBoolean(R.styleable.CirclePageIndicator_centered, defaultCentered);
mOrientation = a.getInt(R.styleable.CirclePageIndicator_android_orientation, defaultOrientation);
mPaintPageFill.setStyle(Style.FILL);
mPaintPageFill.setColor(a.getColor(R.styleable.CirclePageIndicator_pageColor, defaultPageColor));
mPaintStroke.setStyle(Style.STROKE);
mPaintStroke.setColor(a.getColor(R.styleable.CirclePageIndicator_strokeColor, defaultStrokeColor));
mPaintStroke.setStrokeWidth(a.getDimension(R.styleable.CirclePageIndicator_strokeWidth, defaultStrokeWidth));
mPaintFill.setStyle(Style.FILL);
mPaintFill.setColor(a.getColor(R.styleable.CirclePageIndicator_fillColor, defaultFillColor));
mRadius = a.getDimension(R.styleable.CirclePageIndicator_radius, defaultRadius);
mSnap = a.getBoolean(R.styleable.CirclePageIndicator_snap, defaultSnap);
Drawable background = a.getDrawable(R.styleable.CirclePageIndicator_android_background);
if (background != null) {
setBackgroundDrawable(background);
}
a.recycle();
final ViewConfiguration configuration = ViewConfiguration.get(context);
mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration);
}
public void setCentered(boolean centered) {
mCentered = centered;
invalidate();
}
public boolean isCentered() {
return mCentered;
}
public void setPageColor(int pageColor) {
mPaintPageFill.setColor(pageColor);
invalidate();
}
public int getPageColor() {
return mPaintPageFill.getColor();
}
public void setFillColor(int fillColor) {
mPaintFill.setColor(fillColor);
invalidate();
}
public int getFillColor() {
return mPaintFill.getColor();
}
public void setOrientation(int orientation) {
switch (orientation) {
case HORIZONTAL:
case VERTICAL:
mOrientation = orientation;
requestLayout();
break;
default:
throw new IllegalArgumentException("Orientation must be either HORIZONTAL or VERTICAL.");
}
}
public int getOrientation() {
return mOrientation;
}
public void setStrokeColor(int strokeColor) {
mPaintStroke.setColor(strokeColor);
invalidate();
}
public int getStrokeColor() {
return mPaintStroke.getColor();
}
public void setStrokeWidth(float strokeWidth) {
mPaintStroke.setStrokeWidth(strokeWidth);
invalidate();
}
public float getStrokeWidth() {
return mPaintStroke.getStrokeWidth();
}
public void setRadius(float radius) {
mRadius = radius;
invalidate();
}
public float getRadius() {
return mRadius;
}
public void setSnap(boolean snap) {
mSnap = snap;
invalidate();
}
public boolean isSnap() {
return mSnap;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (mViewPager == null) {
return;
}
final int count = mViewPager.getAdapter().getCount();
if (count == 0) {
return;
}
if (mCurrentPage >= count) {
setCurrentItem(count - 1);
return;
}
int longSize;
int longPaddingBefore;
int longPaddingAfter;
int shortPaddingBefore;
if (mOrientation == HORIZONTAL) {
longSize = getWidth();
longPaddingBefore = getPaddingLeft();
longPaddingAfter = getPaddingRight();
shortPaddingBefore = getPaddingTop();
} else {
longSize = getHeight();
longPaddingBefore = getPaddingTop();
longPaddingAfter = getPaddingBottom();
shortPaddingBefore = getPaddingLeft();
}
final float threeRadius = mRadius * 3;
final float shortOffset = shortPaddingBefore + mRadius;
float longOffset = longPaddingBefore + mRadius;
if (mCentered) {
longOffset += ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - ((count * threeRadius) / 2.0f);
}
float dX;
float dY;
float pageFillRadius = mRadius;
if (mPaintStroke.getStrokeWidth() > 0) {
pageFillRadius -= mPaintStroke.getStrokeWidth() / 2.0f;
}
//Draw stroked circles
for (int iLoop = 0; iLoop < count; iLoop++) {
float drawLong = longOffset + (iLoop * threeRadius);
if (mOrientation == HORIZONTAL) {
dX = drawLong;
dY = shortOffset;
} else {
dX = shortOffset;
dY = drawLong;
}
// Only paint fill if not completely transparent
if (mPaintPageFill.getAlpha() > 0) {
canvas.drawCircle(dX, dY, pageFillRadius, mPaintPageFill);
}
// Only paint stroke if a stroke width was non-zero
if (pageFillRadius != mRadius) {
canvas.drawCircle(dX, dY, mRadius, mPaintStroke);
}
}
//Draw the filled circle according to the current scroll
float cx = (mSnap ? mSnapPage : mCurrentPage) * threeRadius;
if (!mSnap) {
cx += mPageOffset * threeRadius;
}
if (mOrientation == HORIZONTAL) {
dX = longOffset + cx;
dY = shortOffset;
} else {
dX = shortOffset;
dY = longOffset + cx;
}
canvas.drawCircle(dX, dY, mRadius, mPaintFill);
}
public boolean onTouchEvent(android.view.MotionEvent ev) {
if (super.onTouchEvent(ev)) {
return true;
}
if ((mViewPager == null) || (mViewPager.getAdapter().getCount() == 0)) {
return false;
}
final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
switch (action) {
case MotionEvent.ACTION_DOWN:
mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
mLastMotionX = ev.getX();
break;
case MotionEvent.ACTION_MOVE: {
final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
final float x = MotionEventCompat.getX(ev, activePointerIndex);
final float deltaX = x - mLastMotionX;
if (!mIsDragging) {
if (Math.abs(deltaX) > mTouchSlop) {
mIsDragging = true;
}
}
if (mIsDragging) {
mLastMotionX = x;
if (mViewPager.isFakeDragging() || mViewPager.beginFakeDrag()) {
mViewPager.fakeDragBy(deltaX);
}
}
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
if (!mIsDragging) {
final int count = mViewPager.getAdapter().getCount();
final int width = getWidth();
final float halfWidth = width / 2f;
final float sixthWidth = width / 6f;
if ((mCurrentPage > 0) && (ev.getX() < halfWidth - sixthWidth)) {
if (action != MotionEvent.ACTION_CANCEL) {
mViewPager.setCurrentItem(mCurrentPage - 1);
}
return true;
} else if ((mCurrentPage < count - 1) && (ev.getX() > halfWidth + sixthWidth)) {
if (action != MotionEvent.ACTION_CANCEL) {
mViewPager.setCurrentItem(mCurrentPage + 1);
}
return true;
}
}
mIsDragging = false;
mActivePointerId = INVALID_POINTER;
if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag();
break;
case MotionEventCompat.ACTION_POINTER_DOWN: {
final int index = MotionEventCompat.getActionIndex(ev);
mLastMotionX = MotionEventCompat.getX(ev, index);
mActivePointerId = MotionEventCompat.getPointerId(ev, index);
break;
}
case MotionEventCompat.ACTION_POINTER_UP:
final int pointerIndex = MotionEventCompat.getActionIndex(ev);
final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
if (pointerId == mActivePointerId) {
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
}
mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
break;
}
return true;
}
@Override
public void setViewPager(ViewPager view) {
if (mViewPager == view) {
return;
}
if (mViewPager != null) {
mViewPager.setOnPageChangeListener(null);
}
if (view.getAdapter() == null) {
throw new IllegalStateException("ViewPager does not have adapter instance.");
}
mViewPager = view;
mViewPager.setOnPageChangeListener(this);
invalidate();
}
@Override
public void setViewPager(ViewPager view, int initialPosition) {
setViewPager(view);
setCurrentItem(initialPosition);
}
@Override
public void setCurrentItem(int item) {
if (mViewPager == null) {
throw new IllegalStateException("ViewPager has not been bound.");
}
mViewPager.setCurrentItem(item);
mCurrentPage = item;
invalidate();
}
@Override
public void notifyDataSetChanged() {
invalidate();
}
@Override
public void onPageScrollStateChanged(int state) {
mScrollState = state;
if (mListener != null) {
mListener.onPageScrollStateChanged(state);
}
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
mCurrentPage = position;
mPageOffset = positionOffset;
invalidate();
if (mListener != null) {
mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
}
}
@Override
public void onPageSelected(int position) {
if (mSnap || mScrollState == ViewPager.SCROLL_STATE_IDLE) {
mCurrentPage = position;
mSnapPage = position;
invalidate();
}
if (mListener != null) {
mListener.onPageSelected(position);
}
}
@Override
public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
mListener = listener;
}
/*
* (non-Javadoc)
*
* @see android.view.View#onMeasure(int, int)
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (mOrientation == HORIZONTAL) {
setMeasuredDimension(measureLong(widthMeasureSpec), measureShort(heightMeasureSpec));
} else {
setMeasuredDimension(measureShort(widthMeasureSpec), measureLong(heightMeasureSpec));
}
}
/**
* Determines the width of this view
*
* @param measureSpec
* A measureSpec packed into an int
* @return The width of the view, honoring constraints from measureSpec
*/
private int measureLong(int measureSpec) {
int result;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
if ((specMode == MeasureSpec.EXACTLY) || (mViewPager == null)) {
//We were told how big to be
result = specSize;
} else {
//Calculate the width according the views count
final int count = mViewPager.getAdapter().getCount();
result = (int)(getPaddingLeft() + getPaddingRight()
+ (count * 2 * mRadius) + (count - 1) * mRadius + 1);
//Respect AT_MOST value if that was what is called for by measureSpec
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}
/**
* Determines the height of this view
*
* @param measureSpec
* A measureSpec packed into an int
* @return The height of the view, honoring constraints from measureSpec
*/
private int measureShort(int measureSpec) {
int result;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
if (specMode == MeasureSpec.EXACTLY) {
//We were told how big to be
result = specSize;
} else {
//Measure the height
result = (int)(2 * mRadius + getPaddingTop() + getPaddingBottom() + 1);
//Respect AT_MOST value if that was what is called for by measureSpec
if (specMode == MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
}
return result;
}
@Override
public void onRestoreInstanceState(Parcelable state) {
SavedState savedState = (SavedState)state;
super.onRestoreInstanceState(savedState.getSuperState());
mCurrentPage = savedState.currentPage;
mSnapPage = savedState.currentPage;
requestLayout();
}
@Override
public Parcelable onSaveInstanceState() {
Parcelable superState = super.onSaveInstanceState();
SavedState savedState = new SavedState(superState);
savedState.currentPage = mCurrentPage;
return savedState;
}
static class SavedState extends BaseSavedState {
int currentPage;
public SavedState(Parcelable superState) {
super(superState);
}
private SavedState(Parcel in) {
super(in);
currentPage = in.readInt();
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeInt(currentPage);
}
@SuppressWarnings("UnusedDeclaration")
public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {
@Override
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
@Override
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
}
- Create
indicator_tags.xmlinsideres -> values
<resources>
<bool name="default_circle_indicator_centered">true</bool>
<color name="default_circle_indicator_fill_color">#FFFF0000</color>
<color name="default_circle_indicator_page_color">#00000000</color>
<integer name="default_circle_indicator_orientation">0</integer>
<dimen name="default_circle_indicator_radius">4dp</dimen>
<bool name="default_circle_indicator_snap">false</bool>
<color name="default_circle_indicator_stroke_color">#FFDDDDDD</color>
<dimen name="default_circle_indicator_stroke_width">1dp</dimen>
<declare-styleable name="ViewPagerIndicator">
<!-- Style of the circle indicator. -->
<attr name="vpiCirclePageIndicatorStyle" format="reference" />
<!-- Style of the icon indicator's views. -->
<attr name="vpiIconPageIndicatorStyle" format="reference" />
<!-- Style of the line indicator. -->
<attr name="vpiLinePageIndicatorStyle" format="reference" />
<!-- Style of the title indicator. -->
<attr name="vpiTitlePageIndicatorStyle" format="reference" />
<!-- Style of the tab indicator's tabs. -->
<attr name="vpiTabPageIndicatorStyle" format="reference" />
<!-- Style of the underline indicator. -->
<attr name="vpiUnderlinePageIndicatorStyle" format="reference" />
</declare-styleable>
<attr name="centered" format="boolean" />
<attr name="selectedColor" format="color" />
<attr name="strokeWidth" format="dimension" />
<attr name="unselectedColor" format="color" />
<declare-styleable name="CirclePageIndicator">
<!-- Whether or not the indicators should be centered. -->
<attr name="centered" />
<!-- Color of the filled circle that represents the current page. -->
<attr name="fillColor" format="color" />
<!-- Color of the filled circles that represents pages. -->
<attr name="pageColor" format="color" />
<!-- Orientation of the indicator. -->
<attr name="android:orientation" />
<!-- Radius of the circles. This is also the spacing between circles. -->
<attr name="radius" format="dimension" />
<!-- Whether or not the selected indicator snaps to the circles. -->
<attr name="snap" format="boolean" />
<!-- Color of the open circles. -->
<attr name="strokeColor" format="color" />
<!-- Width of the stroke used to draw the circles. -->
<attr name="strokeWidth" />
<!-- View background -->
<attr name="android:background" />
</declare-styleable>
<declare-styleable name="LinePageIndicator">
<!-- Whether or not the indicators should be centered. -->
<attr name="centered" />
<!-- Color of the unselected lines that represent the pages. -->
<attr name="unselectedColor" />
<!-- Color of the selected line that represents the current page. -->
<attr name="selectedColor" />
<!-- Width of each indicator line. -->
<attr name="lineWidth" format="dimension" />
<!-- Width of each indicator line's stroke. -->
<attr name="strokeWidth" />
<!-- Width of the gap between each indicator line. -->
<attr name="gapWidth" format="dimension" />
<!-- View background -->
<attr name="android:background" />
</declare-styleable>
<declare-styleable name="TitlePageIndicator">
<!-- Screen edge padding. -->
<attr name="clipPadding" format="dimension" />
<!-- Color of the footer line and indicator. -->
<attr name="footerColor" format="color" />
<!-- Height of the footer line. -->
<attr name="footerLineHeight" format="dimension" />
<!-- Style of the indicator. Default is triangle. -->
<attr name="footerIndicatorStyle">
<enum name="none" value="0" />
<enum name="triangle" value="1" />
<enum name="underline" value="2" />
</attr>
<!-- Height of the indicator above the footer line. -->
<attr name="footerIndicatorHeight" format="dimension" />
<!-- Left and right padding of the underline indicator. -->
<attr name="footerIndicatorUnderlinePadding" format="dimension" />
<!-- Padding between the bottom of the title and the footer. -->
<attr name="footerPadding" format="dimension" />
<!-- Position of the line. -->
<attr name="linePosition">
<enum name="bottom" value="0" />
<enum name="top" value="1" />
</attr>
<!-- Color of the selected title. -->
<attr name="selectedColor" />
<!-- Whether or not the selected item is displayed as bold. -->
<attr name="selectedBold" format="boolean" />
<!-- Color of regular titles. -->
<attr name="android:textColor" />
<!-- Size of title text. -->
<attr name="android:textSize" />
<!-- Padding between titles when bumping into each other. -->
<attr name="titlePadding" format="dimension" />
<!-- Padding between titles and the top of the View. -->
<attr name="topPadding" format="dimension" />
<!-- View background -->
<attr name="android:background" />
</declare-styleable>
<declare-styleable name="UnderlinePageIndicator">
<!-- Whether or not the selected indicator fades. -->
<attr name="fades" format="boolean" />
<!-- Length of the delay to fade the indicator. -->
<attr name="fadeDelay" format="integer" />
<!-- Length of the indicator fade to transparent. -->
<attr name="fadeLength" format="integer" />
<!-- Color of the selected line that represents the current page. -->
<attr name="selectedColor" />
<!-- View background -->
<attr name="android:background" />
</declare-styleable>
</resources>
- Call this from
MainActivitylike
// setup the view pager with its adapter
vpagerProfile.setAdapter(objProfilePageTopListAdapter);
// initialize circular indicator class
mCirclePageIndicator = (CirclePageIndicator)findViewById(R.id.cover_photo_indicator);
mCirclePageIndicator.setPageColor(android.R.color.transparent);
// set viewpager to indicator so it can indicate when you change the page
mCirclePageIndicator.setViewPager(vpagerProfile);
关于android - 带有 TabLayout 的 ViewPager 问题与 AnimatedVectorDrawable,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47242054/
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尝试通过RVM将RubyGems升级到版本1.8.10并出现此错误:$rvmrubygemslatestRemovingoldRubygemsfiles...Installingrubygems-1.8.10forruby-1.9.2-p180...ERROR:Errorrunning'GEM_PATH="/Users/foo/.rvm/gems/ruby-1.9.2-p180:/Users/foo/.rvm/gems/ruby-1.9.2-p180@global:/Users/foo/.rvm/gems/ruby-1.9.2-p180:/Users/foo/.rvm/gems/rub
我的最终目标是安装当前版本的RubyonRails。我在OSXMountainLion上运行。到目前为止,这是我的过程:已安装的RVM$\curl-Lhttps://get.rvm.io|bash-sstable检查已知(我假设已批准)安装$rvmlistknown我看到当前的稳定版本可用[ruby-]2.0.0[-p247]输入命令安装$rvminstall2.0.0-p247注意:我也试过这些安装命令$rvminstallruby-2.0.0-p247$rvminstallruby=2.0.0-p247我很快就无处可去了。结果:$rvminstall2.0.0-p247Search
由于fast-stemmer的问题,我很难安装我想要的任何rubygem。我把我得到的错误放在下面。Buildingnativeextensions.Thiscouldtakeawhile...ERROR:Errorinstallingfast-stemmer:ERROR:Failedtobuildgemnativeextension./System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/rubyextconf.rbcreatingMakefilemake"DESTDIR="cleanmake"DESTDIR=
当我尝试安装Ruby时遇到此错误。我试过查看this和this但无济于事➜~brewinstallrubyWarning:YouareusingOSX10.12.Wedonotprovidesupportforthispre-releaseversion.Youmayencounterbuildfailuresorotherbreakages.Pleasecreatepull-requestsinsteadoffilingissues.==>Installingdependenciesforruby:readline,libyaml,makedepend==>Installingrub
我正在尝试使用boilerpipe来自JRuby。我看过guide从JRuby调用Java,并成功地将它与另一个Java包一起使用,但无法弄清楚为什么同样的东西不能用于boilerpipe。我正在尝试基本上从JRuby中执行与此Java等效的操作:URLurl=newURL("http://www.example.com/some-location/index.html");Stringtext=ArticleExtractor.INSTANCE.getText(url);在JRuby中试过这个:require'java'url=java.net.URL.new("http://www
我意识到这可能是一个非常基本的问题,但我现在已经花了几天时间回过头来解决这个问题,但出于某种原因,Google就是没有帮助我。(我认为部分问题在于我是一个初学者,我不知道该问什么......)我也看过O'Reilly的RubyCookbook和RailsAPI,但我仍然停留在这个问题上.我找到了一些关于多态关系的信息,但它似乎不是我需要的(尽管如果我错了请告诉我)。我正在尝试调整MichaelHartl'stutorial创建一个包含用户、文章和评论的博客应用程序(不使用脚手架)。我希望评论既属于用户又属于文章。我的主要问题是:我不知道如何将当前文章的ID放入评论Controller。
首先回顾一下拉格朗日定理的内容:函数f(x)是在闭区间[a,b]上连续、开区间(a,b)上可导的函数,那么至少存在一个,使得:通过这个表达式我们可以知道,f(x)是函数的主体,a和b可以看作是主体函数f(x)中所取的两个值。那么可以有, 也就意味着我们可以用来替换 这种替换可以用在求某些多项式差的极限中。方法: 外层函数f(x)是一致的,并且h(x)和g(x)是等价无穷小。此时,利用拉格朗日定理,将原式替换为 ,再进行求解,往往会省去复合函数求极限的很多麻烦。使用要注意:1.要先找到主体函数f(x),即外层函数必须相同。2.f(x)找到后,复合部分是等价无穷小。3.要满足作差的形式。如果是加
SPI接收数据左移一位问题目录SPI接收数据左移一位问题一、问题描述二、问题分析三、探究原理四、经验总结最近在工作在学习调试SPI的过程中遇到一个问题——接收数据整体向左移了一位(1bit)。SPI数据收发是数据交换,因此接收数据时从第二个字节开始才是有效数据,也就是数据整体向右移一个字节(1byte)。请教前辈之后也没有得到解决,通过在网上查阅前人经验终于解决问题,所以写一个避坑经验总结。实际背景:MCU与一款芯片使用spi通信,MCU作为主机,芯片作为从机。这款芯片采用的是它规定的六线SPI,多了两根线:RDY和INT,这样从机就可以主动请求主机给主机发送数据了。一、问题描述根据从机芯片手
文章目录git常用命令(简介,详细参数往下看)Git提交代码步骤gitpullgitstatusgitaddgitcommitgitpushgit代码冲突合并问题方法一:放弃本地代码方法二:合并代码常用命令以及详细参数gitadd将文件添加到仓库:gitdiff比较文件异同gitlog查看历史记录gitreset代码回滚版本库相关操作远程仓库相关操作分支相关操作创建分支查看分支:gitbranch合并分支:gitmerge删除分支:gitbranch-ddev查看分支合并图:gitlog–graph–pretty=oneline–abbrev-commit撤消某次提交git用户名密码相关配置g